BuUetin  No.  208 


Series  B,  Descriptive  Geology,  27 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES  II.  WALCOTT,  Directok 


DESCRIPTIVE  GEOLOGY 


OF- 


NEVADA  SOUTH  OF  THE  FORTIETH  PARALLEL 

AND  ADJACENT  PORTIONS  OF 

CALIFORNIA 


BY 


JOSIAH  EDWARD  SPURR 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 
1903 


r-7  V 


r  I  D   ^ 


SEP  3  0  W^ 


CONTENTS. 


Page. 

Introduction 15 

Exj)lanation  of  formation  names 18 

Anbrey  limestone  and  sandstone 18 

dinar  series 18 

Diamond  Peak  qtiartzite 18 

Esmeralda  formation 19 

Eureka  qtiartzite 19 

Grand  Canyon  group 19 

Hamburg  limestone  and  shale 19 

Humboldt  series 20 

Koipato  formation 20 

Lone  Mountain  limestone  ^ 20 

Nevada  limestone 20 

Ogden  quartzite  . 20 

Pogonip  formation 21 

Prospect  Mountain  limestone  and  quartzite , 21 

Red  Wall  limestone 21 

Secret  Canyon  sliale 22 

Star  Peak  formation 22 

Tonto  sliale  and  sandstone 22 

Truckee  formation 22 

Unkar  formation 23 

Wasatch  limestone 23 

Weber  conglomerate 23 

White  Pine  shale 23 

Chapter  I. — Ranges  of  east-central  Nevada 25 

Snake  Range 25 

Topography . 25 

Archean  rocks 26 

Sedimentary  rocks 27 

Cambrian 27 

Silurian 30 

Carboniferous -  32 

Mesozoic  or  Tertiary . 33 

Pliocene 34 

Pleistocene 34 

Igneous  rocks '   35 

Lavas 35 

Dike  rocks 35 

Structure 1 35 

Folds 35 

Faults - 35 

Ores- 36 

3 


4  CONTENTS. 

Chapter  I. — Ranges  of  east-central  Nevada — Contintied.  Page. 

Cedar  Range  and  Clover  Valley  Mountains 36 

Antelope  Range 37 

Sedimentary  rocks 37 

Igneons  rocks -" 37 

Structure 38 

Scliell  Creek  and  Highland  ranges .- 38 

Sedimentary  rocks 38 

Cambrian 38 

Silurian 42 

Devonian . 48 

Carboniferous 43 

Igneous  rocks 44 

Lavas 44 

Dikes 44 

Structure 44 

Folding •- -  -  -  44 

Faulting 45 

Egan  Range 47 

Topography --  47 

Archean  rocks - . . . 47 

Sedimentary  rocks ' 47 

Cambrian --. __-  47 

Silurian j 48 

Devonian 49 

Carboniferous 51 

Igneous  rocks 52 

Lavas 53 

Dikes ■- 53 

Structure 1  —  53 

Folding 53 

Faulting 54 

Ores -• ---   54 

Long  Valley  Range . 54 

Topography 55 

Sedimentary  rocks .  _  -  55 

Carboniferous 55 

Igneous  rocks 56 

Lavas : ■ 56 

Structure 56 

Folding 56 

Golden  Gate  Range  _  - 57 

Topography 57 

Sedimentary  rocks . 57 

Silurian 57 

Devonian 58 

Pleistocene 58 

Igneoiis  rocks 58 

Structure 59 

Folding . 59 

Faulting • 59 

Humboldt  Range 59 

Topography .  59 

Sedimentary  rocks 60 


CONTENTS.      •  5 

Chapter  I. — Ranges  of  east-central  Nevada — Continned.  Page. 
HnmlDoldt  Kange — Continned. 

Igneous  rocks 61 

Structure 61 

Folding 61 

Faulting , . . 61 

White  Pine  Range 61 

Topography 62 

Sedimentary  rocks 62 

Cambrian 1 . 62 

Silurian 63 

Devonian - 63 

Carboniferous 63 

Rhyolite  ash 65 

Igneous  rocks 65 

Lava 65 

Granite 65 

Structure . 65 

Folding 65 

Faulting :.  66 

Relation  of  topography  to  structure 67 

Ores . 68 

Quinn  Canyon  and  G-rant  ranges 68 

Topogi'aphy 68 

Sedimentary  rocks 69 

Cambrian 69 

Silurian 69 

Devonian 71 

Carboniferous . 72 

Pliocene . 72 

Igneous  rocks 72 

Rhyolite  and  granite 72 

Basaltic  volcanics 73 

Quartz-latites •> 73 

Relative  age  of  lavas ---  73 

Structure ---.  73 

Folding 73 

Faulting 75 

Relation  of  structure  to  topography 75 

Worthington  Mountains 76 

Sedimentary  rocks 76 

Igneous  rocks 76 

Structure 77 

Pancake  Range 77 

Topography 77 

Sedimentary  rocks 77 

Carboniferous 77 

Devonian 78 

Tertiary . 78 

Pleistocene  lake  deposition 79 

Gulch  dumps  or  alluvial  fans 79 

Igneous  rocks 79 

Structure 80 

Folding . 80 

Faulting 80 


6  CONTENTS. 

Chapter  I.— Ranges  of  east-central  Nevada — Continued.  Page. 
Pancake  Range — Continued. 

Coal 81 

Diamond  Range 81 

Topography 81 

Sedimentary  rocks .. 81 

Igneous  rocks .  _  83 

Structiire ■ . 83 

Relation  of  structure  to  topography 84 

Ores 84 

Hot  Creek  Range 84 

Sedimentary  rocks 85 

Silurian 85 

Tertiary .. ._ 86 

Igneous  rocks 87 

Lavas 87 

Structure 87 

Ores . 87 

Pinon  Range . 88 

Topography 88 

Sedimentary  rocks _ . 88 

Igneous  rocks 88 

Volcanic  rocks 88 

Structtire . 89 

Monitor  Range 89 

Wahweah  Range 89 

Toquima  Range ' 90 

Topography 90 

Sedimentary  rocks 90 

Igneous  rocks 92 

Lavas - 92 

Dike  rocks 92 

Structure : 92 

Ores - 93 

Toyabe  Range 93 

Topography 93 

Sedimentary  rocks _.__.  94 

Cambrian 94 

Silurian 95 

Devonian 95 

Carbonif  erotis  . 95 

Tertiary '--. 95 

Igneous  rocks 95 

Granite 95 

Rhyolite 96 

Augite-basalt 96 

Relative  age  of  the  igneous  rocks 96 

Structure 96 

Ores 97 

Chapter  II.  —Ranges  of  west-central  Nevada 98 

Reese  River  Range 98 

Topography 98 

Igneous  rocks 99 

Age  of  lavas 99 


CONTENTS.  7 

Chapter  II. — Ranges  of  west-central  Nevada — Continued.  Page. 

Ellsworth  Range 99 

Sedimentary  rocks - 99 

Igneous  rocks 102 

Structure 1 02 

Ores : 103 

Pilot  Mountains 103 

Sedimentary  rocks 103 

Early  Tertiary  or  Mesozoic  series . 103 

Pliocene. 104 

Igneous  rocks . 105 

Pleistocene  oli  vine-basalt 105 

Granitic  rocks 105 

Monte  Cristo  Moimtains , ... 105 

Sedimentary  rocks 105 

Igneous  rocks .... 106 

Desert  Mountains 106 

Gabbs  Valley  and  Gabbs  Valley  Range 107 

Sedimentary  rocks 107 

Early  Tertiary  marls 107 

Pleistocene 108 

Igneous  rocks 108 

Excelsior  Range 109 

Sedimentary  rocks 109 

Limestone  series  (early  Tertiary)  109 

Sandstone-shale  series  (early  Tertiary  or  Mesozoic?)   110 

Pliocene 111 

Igneous  rocks 112 

Lava . ---^ 112 

Granitic  rocks 112 

Structiire 112 

Ores - 113 

Resume 113 

Candelaria  Mountains 1 : 113 

Sedimentary  rocks 113 

Cambrian 113 

Carboniferous 113 

Earlier  Tertiary 114 

Pliocene  beds 114 

Igneous  rocks : 114 

Walker  River  Range 115 

Igneous  rocks 115 

Granular  rocks 115 

Lavas . 116 

Igneous  rocks  showing  transitions  of  texture 116 

Sedimentary  rocks 116 

Pleistocene 116 

Pre-Lahontan  sediments 117 

Smith  Valley  Range 1 117 

Igneous  rocks 118 

Sedimentary  rocks 119 

Pine  Nut  Range . . 120 

Topography 120 

Igneous  rocks.. 120 


«  CONTENTS. 

Chapter  II  — Ranges  of  west-central  Nevada — Continued.  Page. 
Pine  Nut  Range — Continued. 

Sedimentary  rocks 122 

Triassic  limestone 122 

Pliocene  deposits ... 123 

Sweetwater  Range. , ■. 125 

Topography 125 

Igneous  rocks 126 

Post-Pliocene  basaltic  lava 126 

Late  rhyolitic  lava 126 

Late  andesite  and  latite 126 

Earlier  andesites 127 

Earlier  rhyolite 127 

G-ranitic  rocks . . . 127 

Sedimentary  rocks  _  .  _' . . 128 

Pliocene  deposits 128 

Resume '. 128 

Virginia  Range 129 

Igneous  rocks 129 

Sedimentary  rocks 130 

Ancient  limestones 130 

Chapter  III. — Ranges  of  southern  Nevada 131 

Virgin  Range  _  _ 131 

Sedimentary  rocks . 131 

Pre-Tertiary : 131 

Pliocene . 131 

Igneous  rocks 132 

Structure . .. 132 

Colorado  Canyon 133 

Mormon  Range 134 

Sedimentary  rocks 134 

Carboniferous 134 

Pliocene 1 :  _  _  _  _  _  _ 135 

Igneous  rocks ._.... . . 135 , 

Structure .  135 

Muddy  Range 136 

Sedimentary  rocks 137 

Carboniferous 137 

Mesozoic 137 

Tertiary 137 

Igneous  rocks 138 

Structure 138 

Colorado  Range ...    138 

Eldorado  Range . 139 

Meadow  Valley  Canyon . 139 

Topography ... . 139 

Paleozoic  rocks 140 

Rhyolite 140 

Rhyolite-sandstone  series .  _   ....... 140 

Andesite-latite  series 141 

Reddish  dacites  and  rhyolites  and  associated  sediments 142 

Pliocene  beds 143 

Pliocene  rhyolites 146 

Pleistocene  rhyolite  and  basalt 146 


CONTENTS.  9 

Chapter  III. — Ranges  of  soiitliern  Nevada— Continiied.  Page. 
Meadow  A^alley  Canyon— Continued. 

Pleistocene  gravels .. 147 

Sequence  of  events 147 

Meadow  Valley  Range 148 

Sedimentary  rocks 149 

Cambrian 149 

Carbonif eroiis  ._ 149 

Pliocene 150 

Igneous  rocks 150 

Structure 150 

Pahroc  Range 151 

Igneous  rocks 151 

Sedimentary  rocks '- 152 

Structure 153 

Hiko  Range ' 153 

Sedimentary  rocks 152 

Igneous  rocks 153 

Structure 153 

Pahranagat  Range 153 

Sedimentary  rocks ^ 153 

Igneous  rocks —  --1 154 

Structure 154 

Arrow  Canyon  Range 154 

Las  Vegas  Range . 155 

Sedimentary  rocks . 155 

Cambrian 155 

Silurian 156 

Devonian 156 

Carboniferous 156 

Pleistocene 157 

Structure 157 

Timpahute  Range 159 

Sedimentary  rocks 159 

Igneous  rocks 159 

Structure . 160 

Ore  deposits 160 

Desert  Range . 160 

Sedimentary  rocks 160 

Silurian 160 

Devonian 161 

Structure ---  161 

Reveille  Range  -.- 161 

Topography 163 

Sedimentary  rocks 162 

Tertiary " 163 

Igneous  rocks • 163 

Relative  age  of  igneous  rocks 163 

Ore  deposits 163 

Belted  Range 163 

Sedimentary  rocks 164 

Cambrian • 164 

Igneous  rocks '. 164 

Volcanic  rocks 164 

Structure... 164 


10  CONTENTS. 

Chapter  III. — Ranges  of  southern  Nevada — Continued.  Page. 

Spring  Mountain  Range / 164 

Sedimentary  rocks 164 

Cambrian 164 

Carboniferous • 164 

Lower  Carboniferous 169 

Carboniferous  red  beds .  169 

Upper  Carboniferous  limestone 170 

Correlation  with  Grand  Canyon  section . .  172 

Mesozoic 173 

Igneous  rocks 174 

Structure 175 

Ore  deposits 180 

Area  south  of  Spring  Mountain 180 

Kawich  Range 181 

Topography 181 

Sedimentary  rocks 181 

Tertiary . .  181 

Igneous  rocks 1 181 

Ralston  Desert 181 

Igneous  rocks .. 182 

Rhyolites 182 

Basalt 183 

Sedimentary  rocks 183 

Tertiary 183 

Pleistocene 188 

Lone  Mountain - 188 

Igneous  rocks . ,  -  - 184 

Sedimentary  rocks. 184 

Silver  Peak  Range  - 184 

Sedimentary  rocks . 184 

Cambrian 184 

Silurian ■ 185 

Early  Tertiary 185 

Pliocene 185 

Igneous  rocks 186 

Granites .-_ 186 

Volcanic  rocks --  186 

Ore  deposits 186 

Chapter  IV. — Great  Basin  ranges  of  California,  north  of  Mohave  Desert 187 

Grapevine  and  Funeral  ranges 187 

Sedimentary  rocks -  -  188 

Silurian 188 

Devonian :  -  - 188 

Tertiary -  189 

Pleistocene 191 

Igneous  rocks -- -  192 

Granular  rocks 192 

Olivine-basalt  at  Furnace  Creek 192 

Andesite  at  Furnace  Creek . 192 

Volcanics  north  of  Furnace  Creek 192 

Structure 193 

Resume 194 


CONTENTS.  11 

Chapter  IV. — Great  Basin  ranges  of  California,  etc.— Continued.  Page. 

Amargosa  Valley 195 

Metamorpliic  rocks 195 

Sedimentary  rocks 195 

Tertiary 195 

Structure 195 

Kingston  Range 195 

Sedimentary  rocks 196 

Cambrian 196 

Devonian . 197 

Mesozoic 198 

Tertiary 198 

Igneous  rocks 199 

Structure :.-_._..-_ 199 

Opal  or  Clarks  Peak  Mountains 200 

Ore  deposits 200 

Panamint  Range 200 

Sedimentary  rocks  - . 201 

Cambrian 201 

Silurian  and  Carboniferous .._.---  202 

Early  Tertiary 202 

Late  Tertiary - 202 

Pleistocene  _  - . 203 

Igneous  rocks 203 

Granite 203 

Volcanic  rocks -  203 

Structure---- 204 

Ore  deposits 205 

Leacli  Point  and  Burnt  Rock  Mountains 205 

Sedimentary  rocks 205 

Limestone 205 

Eocene 206 

Igneous  rocks 206 

Granite 206 

Volcanic  rocks 206 

Structure .- 206 

White  Mountain  Range 206 

Topography 207 

Sedimentary  rocks 207 

Cambrian 207 

Silurian 208 

Carboniferous 208 

Triassic --- -  208 

Pliocene 209 

Igneous  rocks 210 

Granitic  rocks -  210 

Volcanic  rocks 211 

Ore  deposits 211 

Structiire 212 

Darwin  or  Argus  Range 212 

Sedimentary  rocks •  212 

Igneous  rocks 212 

Granite 212 

Volcanic  rocks 212 

Ore  deposits  ._ - - 213 


12  CONTENTS. 

Chapter  IV. — Great  Basin  ranges  of  California,  etc. — Continued.  Page. 

Slate  Range 313 

Sedimentary  rocks 213 

Paleozoic _....   213 

Tertiary .   213 

Igneous  rocks 213 

Volcanic  rocks 213 

Coso  Range 214 

Igneous  rocks 214 

Granite 214 

Volcanic  rocks 214 

El  Paso  Range .  _' 214 

Sedimentary  rocks 214 

Early  Tertiaries . 215 

Igneous  rocks 215 

Granite 215 

Volcanic  rocks 215 

Structure . 216 

Ore  deposits . 216 

Hills  from  Randsbtirg  east  to  Pilot  Knob 216 

Sedimentary  rocks ■ 216 

Arkoses ...  216 

Igneous  rocks 217. 

Ore  deposits 217 

Sierra  Nevada 218 

Sedimentary  rocks 218 

Cambrian 218 

Carboniferous 219 

Triassic... . 219 

Jurassic _  219 

Igneous  rocks 219 

Structure 220 

Index : 223 


ILLUSTHATIONS. 


Page. 
Plate  I.  Geological  reconnaissance  map  of  Nevada  south  of  the  fortieth 

parallel,  with  adjacent  California : In  pocket 

II.  Map  showing  position  of  geological  reconnaissance  map  and  chief 

data  nsed  in  its  compilation 15 

III.  ^-1,  Jeff  Davis  or  Wheeler  Peak,  Snake  Range,  from  Robinson's 

ranch:  B,  North  end  of  Schell  Creek  Range,  from  Antelope 
Range 26 

IV.  A,  Snake   Mountains  north  of   Robinson's  ranch;    B,  Antelope 

Range,  east  side BO 

V.  A,  East  face  of  low  mountain  range  west  of  Egan  Range  at  Ely; 
B,  Tertiary  volcanic  cone.  Pancake   Range,  east  side  of  Hot 

Creek 50 

VI.  ^-i,  Rhyolite  walls  of  Meadow  Valley  Canyon  at  Carson's  ranch; 
B,  Pliocene  conglomerate  in  Meadow  Valley  Canyon  at  Kane 

Spring 140 

VII.  ^4,  North  scarp  of  Stonewall  Mountain,  Ralston  Desert;  i?.  Pyra- 
mid Peak,  Grapevine  Range,  from  the  head  of  Furnace  Creek, .  183 
VIII.  Sketch  structure  section  of  Grapevine  Range  at  Furnace  Creek: 
A,  Sketch  cross  section  of  the  southern  end  of  the  Grapevine 
Range,  at  Furnace  Creek;  B,  Sketch  longitudinal  section  from 
the  southern  end  of  the  Grapevine  Range  southward  across 

Furnace  Creek 194 

Fig.  1.  Sketch  section  5  miles  north  of  Hamilton  across  White  Pine  Range 

to  the  eastern  edge  of  Long  Valley  Range fi6 

2.  Sketch  section  through  White  Pine  Range  at  Hamilton  at  the  junc- 

tion of  White  Pine  and  Long  Valley  ranges .  _  _ 66 

3.  Generalized  section  on  a  line  drawn  a  little  north  of  east  across 

Quinn   Canyon  and  Grant  ranges;   at  the  north  end  of  Quinn 
Canyon  Range ,  but  sou.th  of  the  fault  line  _   74 

4.  Sketch  section  of  east  front  of  Grant  Range,  taken  5  miles  north  of 

locality  of  fig.  3 75 

5.  Generalized  sketch  section  of  north  end  of  Quinn  Canyon  Moun- 

tains          75 

6.  Generalized  sketch  cross  section  of  Pancake  Range  at  north  side  of 

pass  at  Twin  Springs 80 

7.  Generalized  sketch  section  across  Hot  Creek  Range  at  Hot  Creek  _ .         88 

8.  Section  of  Eldorado  Canyon ,  Pinenut  Range 121 

9.  Sketch  section  of  wall  of  arroyo  in  bottom  of  Eldorado  Canyon, 

Pinenut  Range 123 

10.  Generalized  cross  section  of  northern  end  of  Mormon  Range 186 

11.  Cross  section  of  Muddy  Range,  after  R.  B.  Rowe 138 

13 


14  ILLUSTKATIONS. 

Page. 
Fig.  12.  Sketch  section  of  east  wall  of  Meadow  Valley  Canyon  just  south  of 

Carson's  ranch j4j 

13.  Sketch  section  of  west  wall  of  Meadow  Valley  Canyon  at  same  local- 

ity as  fig.  12 141 

14.  Sketch  of  east  side  of  Meadow  Valley  Canyon  near  locality  of  fig- 


ures 13  and  13_ 


142 


15.  Sketch  section  of  south  wall  of  Hackberry  Canyon  near  junction 

with  Meadow  Valley  Canyon I44 

16.  Sketch  section  of  north  wall  of  Meadow  Valley  Canyon  3  miles 

southwest  of  mouth  of  Hackberry  Canyon I44 

17.  Sketch  section  on  east  wall  of  Meadow  Valley  Canyon  from  Kane 

Spring  to  Grapevine  Spring I45 

18.  Sketch  section  of  west  wall  of  Meadow  Valley  Canyon  at  Grapevine 

Spring 14g 

19.  Sketch  section  of  wall  of  Hackberry  Canyon  at  Hackberry  Spring.       147 

20.  Sketch  section  of  southern  end  of  Meadow  Valley  Range  extended 

through  the  New  Mountain  Ridge 151 

21.  Generalized  sketch  cross  section  of  Reveille  Range  near  Reveille  _       162 

22.  Generalized  sketch  sections  across  Spring  Motmtain  Range .    176 

23.  Section  showing  great  fault  at  Olcott  Peak,  after  R.  B.  Rowe 177 

24.  Cross  section  of  southern  end  of  Spring  Moiintain  Range  (east  and 

west) ,  showing  great  fault  several  miles  north  of  the  point  rep- 
resented in  fig.  23 173 

25.  Cross  section  of  Bird  Spring  Mountains  (southern  spur  of  Spring 

Mountain  Range) ,  after  R.  B.  Rowe I79 


U.    S.    GEOLOGICAL    SURVEY 


BULLETIN    NO.   208    PL.   II 


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l^ZAJP  SHO^VH^G  POSITION  OF 

GEOLOGICAL  IlECOT^lSIAISSAN^CE  MAP 

^AND  CHIKF  X)ATA.TJSED  UST  IT  S  C  0MT>rCATI01Sr 

Scale 


DESCRIPTIVE  GEOLOGY  OF  NEYADA  SOUTH  OF  THE 
FORTIETH  PARALLEL  AND  ADJACENT  PORTIONS  OF 
CALIFORNIA. 


By  JosiAH  Edward  Spurr. 


I N  T  R  O  D  U  C  T I O  N  . 

The  field  work  upon  which  the  jiresent  bulletin  is  based,  so  far  as 
the  writer's  labors  are  concerned,  was  done  in  the  summer  and  fall  of 
1899.  After  visiting  the  Wasatch  Range  to  study  briefly  the  Wasatch 
Paleozoic  section,  as  determined  by  the  Fortieth  Parallel  Survey,  the 
writer  proceeded  to  Eureka,  in  Nevada,  and  there  spent  two  weeks  in 
studjnng  that  section,  the  best  and  most  complete  yet  discovered  in 
the  far  West.  Feeling  finally  ready  for  untried  ground,  the  expedi- 
tion, consisting,  besides  the  writer,  of  a  teamster,  a  cook,  and  an  assist- 
ant, left  Eureka  and  proceeded  southeastward  to  Hamilton,  and  then 
to  Elj^  From  Elj^  the  route  ran  to  Osceola  in  the  Snake  Creek  Range, 
thence  across  that  range  and  northward  up  Snake  Valley  to  Pleasant 
Valley,  where  a  westward  course  was  again  taken.  Schellbourne 
and  Cherry  Creek,  the  latter  in  the  Egan  Range,  were  next  visited, 
and  thence  the  waj^  led  northwestward  to  Ruby  Lake,  and  so  back  to 
Eureka.  During  part  of  this  journey  some  of  the  region  which  had  been 
mapped  by  the  Fortieth  Parallel  Survej^  was  traversed,  this  route  being 
purposely  chosen  so  as  to  permit  study  in  the  field  of  the  application 
of  the  Fortieth  Parallel  geologic  section.  After  replenishing  sup- 
plies at  Eureka  the  expedition  took  the  road  southward  to  Hot  Creek, 
and  thence  proceeded  westward  to  Belmont.  The  country  to  Carson 
was  then  traversed,  the  more  or  less  inactive  mining  camps  of  lone, 
Ellsworth,  and  Downieville  and  the  Indian  reservation  at  Walker 
Lake  being  passed.  At  Carson  a  short  time  was  spent,  and  the  famous 
Comstock  lode  and  the  southern  end  of  the  Virginia  Range  were 
visited.  From  Carson  the  route  was  southwestward  past  Wellington, 
Hawthorne,  Sodaville,  Columbus,  and  Silver  Peak,  to  Lida.  From 
Lida  the  course  was  again  toward  the  east,  and  the  State  of  Nevada 
was  crossed  again  by  way  of  tlie  Ralston  Desert,  Twin  Springs,  and 
White  River,  to  Pioche.  From  Pioche,  Meadow  Valley  Canyon  was 
followed  southward  to  the  Indian  reservation  at  Moapa  or  West  Point, 
not  far  from  the  Colorado,  then,  a  turn  to  the  west  being  made,  the 

15 


16  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PAKALLEL.     [bull. 208. 

State  was  crossed  a  third  time,  by  way  of  Indian  Springs  and  Pali- 
rumji  Valley,  into  California.  Funeral  Range  was  crossed  and  Death 
Valley  entered  at  Furnace  Creels:.  From  here  the  expedition  went 
southward,  and,  crossing  the  Panamint  Range  at  Windy  Gap,  pro- 
ceeded by  way  of  Granite  Wells  to  Johannesburg.  From  Johannes- 
burg the  party  proceeded  across  the  Mohave  Desert,  crossing  the 
Santa  Fe  Railroad  at  Hinckley.  Finally  San  Bernardino  was  readied, 
which  was  the  end  of  the  journey.  This  trip  lasted  about  five  months, 
and  comprised  over  2,000  miles  of  actual  travel. 

The  primary  object  of  tlie  expedition  was  to  make  the  roughest  kind 
of  a  general  geologic  map,  such  as  might  fill  up  the  great  gaps  in  the 
map  of  the  western  United  States.  It  being  the  intention  of  the  Sur- 
vey to  publish  a  general  geologic  map  of  the  United  States  on  a  scale 
of  about  40  miles  to  the  inch,  no  great  amount  of  detail  was  advisable 
or  possible.  On  account,  also,  of  the  rough  and  inaccurate  manner  in 
which  much  of  the  region  of  the  western  United  States  has  been 
already  mapped,  it  was  not  advisable  to  undertake  to  do  any  work  of 
higher  grade. 

In  order  to  accomplish  the  style  of  mapping  desired  with  as  much 
economy  of  time  and  labor  as  possible,  the  writer  determined  to  avoid 
anj^  duplication  between  his  route  and  those  already  traveled  by  geolo- 
gists, and  carefully  planned  his  journeys  with  that  end  in  view.  On 
the  north  the  area  which  he  undertook  to  investigate  was  bounded  by 
the  geologic  maps  of  the  Fortieth  Parallel  Survey  (atlas  maps  4  and  5) ; 
on  the  east  it  was  bounded  by  the  geologic  maps  of  the  Wheeler  sur- 
vey; and  on  the  west  chiefly  by  a  reconnaissance  map  of  the  Sierra 
Nevada  published  by  Mr.  H.  W.  Turner  in  the  Seventeenth  Annual 
Report  of  the  United  States  Geological  Survey,  Part  I ;  on  the  south 
there  was  no  definite  boundary. 

Within  the  area  to  be  mapped,  about  the  only  important  journey 
that  had  been  made  by  a  geologist  had  been  accomplished  by  Mr. 
Gilbert  in  1871,  while  with  the  Wheeler  Topographic  Survey.  His 
route,  with  the  other  boundaries  already  mentioned,  is  shown  on  PI.  II. 
The  writer  was  able  to  so  plan  his  route  with  reference  to  the  work 
of  Mr.  Gilbert  and  to  the  maps  which  bounded  the  area  that  hardly 
any  point  in  the  region  examined  can  be  found  which  is  more  than  30 
miles  from  a  point  of  observation.  This  in  any  country  would  prob- 
ably be  sufficient  for  a  reconnaissance  map  on  a  scale  of  40  miles  to 
the  inch,  but  in  the  Great  Basin  region  of  Nevada  and  California  the 
conditions  are  especially  favorable,  so  that  a  map  can  be  made  having 
far  more  value  than  in  ordinary  regions.  The  clear  air,  the  lack  of 
vegetation,  and  the  general  continuity  of  formations  parallel  with  the 
north-south  ranges  all  combine  to  make  a  reconnaissance  more  satis- 
factory than  usual.  The  attitude  of  strata  or  a  conspicuous  formation 
maj"  often  be  followed  15  or  20  miles  along  the  front  of  a  mountain,  by 
the  aid  of  a  field  glass,  from  a  single  point. 


SPURR]  INTRODUCTION.  17 

The  foregoing  explauation  iudicates  clearly  euougli  the  character 
of  the  ma]3  aud  the  weight  which  should  be  placed  upon  it.  The 
data  along  the  lines  of  reconnaissance,  often  obtained  on  forced 
marches  of  20  or  30  miles  a  day,  are  oftentimes  meager  and  nnsatis- 
factor3^  Between  the  lines  of  actual  travel  the  data  are  still  less 
reliable,  and  a  great  deal  of  the  mapping  has  been  done  simjply  from 
inference.  Thus  it  is  probable  that  anyone  examining  closely  the 
detail  of  the  map  will  find  it  nearly  all  inaccurate,  while  one  looking 
for  the  main  principles  will  recognize  the  general  correctness  of  the 
mapping  and  the  value  of  the  map  as  a  pioneer. 

The  inaccuracy  of  the  map  is  unavoidably  heightened  by  the  lack 
of  a  suitable  topographic  base.  The  present  base  has  been  prepared 
in  a  very  rough  and  unsatisfactory  way,  chiefly  from  the  Wheeler  and 
other  early  surveys.  It  is  a  source  of  regret  to  the  author  of  the  bul- 
letin that  so  rough  a  topographic  map  must  be  presented  as  the  vehicle 
for  his  geologic  information. 

Within  the  text  of  the  bulletin  an  effort  has  been  made  to  give 
clearly  the  known  facts  concerning  the  geology,  whether  obtained  by 
the  writer  or  previousl3\  Fidl  credit  is  given  to  previous  work, 
although  it  can  not  alwaj^s  be  given  in  the  map  compiled  from  this 
information.     The  chief  sources,  however,  are  shown  on  PL  II." 

The  writer  has  judged  it  most  advisable  to  confine  the  text  to 
descriptive  matter.  General  results,  especially  those  involving  appli- 
cation of  theory,  have  been  withheld  or  published  separately.  Among 
these  general  results  the  author  has  published  two  papers  on  volcan- 
ism  in  the  Journal  of  Geologj^  entitled  The  Succession  and  Relation 
of  Lavas  of  the  Great  Basin  Region  (October-November,  1900),  and 
Transitions  of  Texture  in  certain  Tertiary  Igneous  Rocks  of  the  Great 
Basin.  A  petrographic  paper  on  Quartz-muscovite  E'ock  from  Bel- 
mont, Nev.,  has  been  published  in  the  American  Journal  of  Science 
(November,  1900).  A  paper  on  the  Origin  and  Structure  of  the 
Basin  Ranges  was  read  before  the  Geological  Society  of  America  at 
Albany,  December,  1900. 

«  After  the  above  was  written,  and  while  the  bulletin  was  in  galley  proof,  new  information  was 
received  as  a  result  of  the  studies  of  Messrs.  Weeks  and  Rowe,  of  the  U  S.  Geological  Survey.' 
The  studies  of  Mr.  Weeks  were  made  in  1900;  those  of  Mr.  Rowe  in  1900  and  1901,  The  results  of 
these  have  been  incorporated  in  the  bulletin. 

Bull.  208—03 2 


EXPLANATION  OF  FORMATION  NAMES. 

The  following  is  a  brief  explanation  of  formation  names  used  in  this 
work.     Names  are  arranged  alphabetically. 

Aubrey  limestone  and  sandstone. — These  names  were  applied  by 
Messrs.  Gilbert  and  Marvine  in  1871  to  formations  in  the  Colorado 
Canyon  region.  The  limestone  lies  above  the  sandstone  and  has  a 
thickness  of  820  feet  on  Kanab  Ci-eek.  At  a  few  points  in  the  top- 
most layer  were  found  a  group  of  shells  suggesting  the  Permo-Carbon- 
iferous  of  the  Mississippi  Valley,  indicating  that  the  great  Paleozoic 
lithologic  change  at  this  horizon  marks  the  absolute  close  of  the 
Carboniferous  age.  Lithologically  the  limestone  is  characterized  by 
a  great  abundance  of  chert,  which  toward  the  top  sometimes  consti- 
tutes half  the  mass.  Near  the  middle  it  is  in  some  places  interruj^ted 
by  a  belt  of  shale  with  gyi)suni. 

The  underlying  Aubrey  sandstone  series  has  a  thickness  in  the 
Aubrey  cliffs  and  along  the  Grand  Canyon  of  about  1,000  feet.  In 
every  exjjosu re  a  portion  of  this  bod}^  is  massive  and  cross  bedded  and 
another  portion  soft  and  gypsiferous,  but  the  order  of  these  parts  is 
not  constant.  The  sandstones  contain  no  fossils,  but  an  intercalated 
limestone  below  the  middle  of  the  series  at  Canyon  Creek  bears  famil- 
iar Coal  Measures  shells." 

Chuar  series.— This  name  was  introduced  by  Mr.  C.  D.  Walcott  in 
1883  for  a  part  of  the  LoAver  Cambrian  of  the  Grand  Canyon  region. 
Mr.  Walcott  divided  the  Grand  Canyon  group  of  Major  Powell  into  a 
lower  and  an  upper  division,  the  Grand  Canyon  and  the  Chuar.  In  1886 
the  reference  to  the  Lower  Cambrian  was  changed  to  pre-Cambrian. 
In  1890  these  strata  were  referred  to  the  Algonkian  system.  In  1894 
Mr.  Walcott  again  classified  the  Algonkian,  dividing  the  Grand 
Canj^on  series  of  this  system  into  the  upper  (Chuar)  series  and  the 
lower  (Unkar)  series.  The  Chuar  is  separated  by  an  unconformity 
from  the  overlying  Cambrian  (Ton to  series).* 

Diamond  Peak  quarizite. — -This  name  Avas  given  by  Mr.  Hague  to 
the  lowest  lithologic  member  of  the  Carboniferous  at  Eureka,  Nev. 
At  this  place  the  Diamond  Peak  quartzite  consists  of  3,000  feet  of  mas- 
sive gray  and  brown  quartzites,  with  broAvn  and  green  shales  at  the 
summit.     It  underlies  3,800  feet  of  heavy  bedded,  dark-blue  and  graj^ 

nU.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  177. 
6  Fourteenth  Ann.  Kept.  U.  S.  Geol.  Survey,  Part  II,  p.  506. 
18 


spuRR.]  DESCRIPTIONS    OF    FORMATIONS.  19 

Lower  Coal  Measures  limestone,  which  contains  intercalated  beds  of 
chert  and  argillaceous  beds  near  the  base.  The  Diamond  Peak  quartz- 
ite  is  not  a  persistent  lithologic  terrane,  and  is  not  recognizable  Avith 
confidence  at  any  great  distance  from  tlie  Enreka  section. 

Es)neralda  formation. — This  name  was  ap^jlied  by  Mr.  11.  W.  Tur- 
ner" to  Tertiary  formations  in  the  Silver  Peak  Range,  in  tlie  west- 
ern part  of  Nevada.  These  deposits  consist  of  sandstones,  shales, 
volcanic  tuffs,  breccias,  conglomerates,  and  great  thicknesses  of 
lacustrine  marls.  Coal  beds  and  plant  remains  occur;  also  fossil 
shells  and  fish  bones.  From  the  evidence  afforded  b}^  these  fossils, 
the  age  of  the  beds  was  broadly  determined  as  late  Eocene  or  early 
Miocene. 

Eureka  quartzite. — This  name  was  applied  by  Mr.  Hague  to  the  mid- 
dle of  the  three  divisions  of  the  Silurian  in  the  Eureka  district.  This 
division  here  consists  of  500  feet  of  compact  vitreous  quartzite,  white 
or  blue  in  color,  and  j)assing  into  rock  of  reddish  tints  near  the  base, 
with  indistinct  bedding.  It  overlies  the  Pogonip  limestone,  and  is 
separated  from  the  overlying  Silurian  Lone  Mountain  limestone  by  an 
unconformity.  The  Eureka  quartzite  appears  to  be  one  of  the  most 
persistent  lithologic  terranes  of  the  Nevada  Paleozoic.  It  has  been 
recognized  over  a  wide  area. 

Grand  Canyon  groiqj. — The  name  Grand  Canyon  groux3  was  given 
by  Ma  j.  J.  W.  Powell  to  the  strata  in  the  Grand  Canyon  region  beneath 
the  Tonto  sandstone  and  above  the  Grand  Canyon  schists.  The 
latter  were  referred  tentatively  to  the  Eozoic,  and  the  10,000  feet  of 
the  Grand  Canyon  group  to  the  Silurian.  In  1883  Mr.  C.  D.  Walcott 
referred  Major  Powell's  Grand  Canyon  group  to  the  Lower  Cambrian 
and  separated  it  into  an  upper  and  a  lower  division,  the  Grand  Canyon 
and  the  Chuar.  In  1886  these  rocks  were  referred  bj^  Mr.  Walcott  to 
the  pre-Cambrian,  and  in  1890  to  the  Algonkian.  In  1894  Mr.  Wal- 
cott subdivided  the  Grand  Canyon  group  of  the  Algonkian  into  the 
Chuar  and  the  Unkar  series.  The  Grand  Canyon  group  is  separated 
by  an  unconformity  from  the  overlying  Cambrian  (Tonto  sandstone), 
and  by  a  great  unconformity  from  the  underlying  Vishnu  series  of 
schists. 

Hamhiirg  limestone  a7id  shale. — The  Hamburg  limestone  and  shale 
are  the  uppermost  divisions  of  the  Cambrian  as  defined  by  Mr.  Hague 
in  the  Eureka  district,  Nevada.  The  Hamburg  shale  lies  at  the  very 
top  and  consists  of  350  feet  of  yellow  argillaceous  shale  containing 
layers  of  chert  nodules,  especially  near  the  top.  The  underlying 
Hamburg  limestone  consists  of  1,200  feet  of  dark-gray  granular  lime- 
stone, with  only  slight  traces  of  bedding.  The  Hamburg  shale  is 
characterized  by  well-developed  Upper  Cambrian  fauna.* 

a  Am.  Geol.,  Vol.  XXV,  p.  168. 

&  Second  Ann.  Bept.  U.  S,  Geol.  Survey,  p.  37;  Third  Ann.  Kept.,  p.  255. 


20  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.308. 

Huitiboldt  series. — This  name  was  applied  by  King"^'  to  a  series  of 
loose,  friable  Tertiar}^  rocks,  carrying  very  recent  fresh-water  niol- 
lusks.  This  series  is  found  at  intervals  all  over  the  northern  portion 
of  the  Great  Basin  region,  from  the  Sierra  Nevada  into  Utah.  Mr. 
King  regard-ed  all  these  beds,  which  from  their  fossils  were  referred 
to  the  late  Pliocene,  as  lake  deposits  and  as  representing  the  sedi- 
ment of  a  single  lake  out  of  which  the  numerous  lofty  mountain 
masses  rose  in  a  complicated  system  of  islands. 

Koipato  formation. — This  name  was  applied  by  Mr.  King*  to  one  of 
the  two  chief  divisions  of  the  Triassic  in  western  Nevada.  He 
describes  the  Koipato  as  made  up  of  siliceous  and  argillaceous  beds, 
whose  chemical  peculiaritj^  is  the  almost  total  absence  of  soda  and 
lime  and  the  high  percentage  of  alumina  and  potash.  This  series  has 
an  observable  thickness  of  about  6,000  feet,  with  an  unknown  quan- 
tity to  be  added  for  the  unseen  beds  at  the  bottom.  Tlie  Koipato  is 
overlain  by  the  Triassic  Star  Peak  series. 

Lone  Mou7itai7i  limestone. — This  name  was  given  by  Mr.  Hague 
to  the  uppermost  division  of  the  Silurian  in  the  Eureka  district.  It 
consists  of  1,800  feet  of  strata.  At  the  base  are  black  gritty  beds 
passing  into  light-gray  siliceous  rocks  with  all  traces  of  bedding 
obliterated.  There  are  Trenton  fossils  at  the  base  and  Halysites  in 
the  upper  portion.  The  formation  is  separated  from  the  underlying 
Silurian  Eureka  quartzite  by  an  unconformity,  and  is  overlain  con- 
formably by  the  Devonian  Nevada  limestone. 

Nevada  limestone. — The  Nevada  limestone,  as  defined  b^''  Mr. 
Hague,''  is  the  lower  member  of  the  Devonian  series  at  Eureka.  It 
consists  of  6,000  feet  of  limestone.  The  lower  horizons  are  indis- 
tinctly bedded,  with  saccharoidal  texture  and  gray  color,  passing  up 
into  distinctly  bedded  strata,  reddish  brown  and  graj^^  in  color,  fre- 
quently finely  striped,  ijroducing  a  variegated  appearance.  The 
upper  horizons  are  massive,  well  bedded,  bluish  black  in  color,  and 
highly  fossiliferous.  The  Nevada  limestone  overlies  the  Silurian 
Lone  Mountain  limestone  at  Eureka  and  is  overlain  by  the  Devonian 
White  Pine  shale. 

Ogden  quartzite. — This  term  was  applied  by  King'^  to  a  sheet  of 
siliceous  sediment,  in  general  compacted  into  a  quartzite.  Mr.  King 
stated  that  this  formation  had  a  remarkable  evenness  over  all  the 
Paleozoic  area  west  of  and  including  the  Wasatch.  In  its  typical 
locality,  Ogden  Canyon,  AVasatch  Range,  it  was  stated  to  be  1,200 
or  1,400  feet  thick;  at  Cottonwood  Canyon  1,000  feet,  and  in  middle 
Nevada  from  800  to  900  feet.  In  Ogden  Canyon  it  is  bounded  at 
the  top  and   bottom  b}^  thin   beds  of  greenish-gray  argillites;  and 

n  U.  S.  Geol.  Expl  Fortieth  Par.,  Vol.  I,  p.  434. 
blbid.,p.  346. 

c  Third  Ann.  Rept.  U.  S.  Geol.  Survey,  p.  2ba. 
rtOp.  cit.,  p.  234. 


SPURR]  DESCKIPTIONS    OF    FORMATIONS.  21 

about  the  middle  of  the  qnartzite  is  a  thin  bed  of  white,  slightly  silice- 
ous marble.  No  fossils  were  found  in  this  formation,  but  it  was 
referred  to  the  Devonian,  since  it  was  found  to  overlie  the  Pogonip 
limestone,  which  contains  Lower  Helderberg  fossils,  and  is  overlain 
by  the  Wasatch  limestone,  whose  basal  beds  contain  Upper  Helder- 
berg forms. 

Pogonip  formation. — King'*  described  the  Pogonip  limestone  in 
middle  Nevada,  in  the  regions  of  White  Pine,  Eureka,  Pinyon,  and 
Roberts  Peak  ranges,  as  being  Cambrian  in  the  lower  half  and  con- 
taining Silurian  fossils  in  its  upper  2,000  feet.  In  the  Eureka  sec- 
tion, the  term  Pogonip  was  limited  by  Mr.  Hague  ^  to  the  Silurian 
portion  of  the  series,  which  consists  of  2,700  feet  of  interstratified 
limestone  and  argillites,  with  arenaceous  beds  at  the  base>  These 
rocks  pass  into  pure,  fine-grained  limestone  of  a  bluish-gray  color, 
distinctly  bedded.  They  are  highly  fossiliferous.  The  Pogonip  lime- 
stone is  the  lowest  member  of  the  Silurian  of  the  Eui'eka  section.  -  It 
overlies  the  topmost  member  of  the  Cambrian,  the  Hamburg  shale, 
conformably,  and  is  conformably  overlain  by  the  Silurian  Eureka 
qnartzite. 

Prospect  Mountain  limestone  and  quartziie. — These  names  were 
given  by  Mr.  Hague  ^  to  the  two  lowest  divisions  of  the  Cambrian  sec- 
tion at  Eureka,  Nev.  The  Prospect  Mountain  qnartzite  is  the  lowest 
and  consists  of  1,500  feet  of  bedded  brownish- white  quartzites,  weath- 
ering dark  brown  but  Avhiter  near  the  summit.  The  quartzites  contain 
intercalated  thin  laj^ers  of  arenaceous  shales,  and  are  ferruginous 
near  the  base. 

The  qnartzite  is  overlain  by  the  Prospect  Mountain  limestone, 
which  consists  of  3,050  feet  of  gray,  compact  limestone  of  rather  light 
shade,  traversed  by  thin  seams  of  calcite.  It  has  very  imperfect  bed- 
ding iDlanes.  The  upper  portion  of  the  Prospect  Mountain  quartzites 
is  characterized  by  the  Olenellus  or  Lower  Cambrian  fauna,  and  the 
Prospect  Mountain  limestone  by  the  Middle  Cambrian  fauna  of  the 
Rocky  Mountain  section. 

Red  Wall  limestone.- — This  name  was  applied  by  Messrs.  Gilbert 
and  Marvine  '^  to  a  heavy  Carboniferous  limestone  in  the  Grand  Can- 
yon region.  This  limestone  has  a  gray  color  on  fresh  fracture,  but 
shows  a  red  rust  on  weather-stained  cliffs.  It  is  generally  heavy 
bedded  to  massive.  At  the  top  sandstone  alternates  with  limestone 
for  from  200  to  500  feet.  Through  its  lower  half  the  limestone  is 
interrupted  by  occasional  shaly  bands.  The  average  total  thickness 
is  2,500  feet.  Fossils  are  abundant  near  the  top  but  rare  in  the  lower 
part.     The  upper  portion  contains  Coal  Measures  fossils.     The  lowest 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.  232. 

b  Third  Ann.  Rept.  U.  S.  Geol.  Survey,  p.  255. 

cU.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  178. 


22  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

fossils  were  obtained  just  below  the  middle  of  the  series,  and  were 
doubtfully  referred  to  the  Lower  Carboniferous. 

Secret  Canyon  shale. — This  name  was  applied  bj'- Mr.  Hague «  to 
a  division  of  the  Cambrian  in  the  Eureka  district  overlying  the 
Prospect  Mountain  limestone  and  underlying  the  Hambiirg  lime- 
stone. It  consists  of  1,G00  feet  of  yellow  and  gray  argillaceous 
shales,  passing  into  shaly  limestone.  This  formation  is  characterized 
by  a  fauna  that  may  be  referred  to  the  upper  portion  of  the  Middle 
Cambrian. 

Star  Peak  formation. — This  name  was  applied  by  Mr.  King''  to  the 
uppermost  of  the  two  great  divisions  of  the  Triassic  of  western 
Nevada.  The  series  consists  of  10,000  feet  of  strata,  made  up  of  an 
alternation  of  three  great  limestone  zones  and  three  interposed  quartz- 
ite  zones.  The  upper  two  quartzites  represent  moderately  pure  sili- 
ceous sediment,  while  the  lower  quartzite  closely  follows  the  physical 
and  chemical  peculiarities  of  the  underlying  Triassic  Koipato  series. 
The  fossils  of  these  limestones  are  marvelously  like  the  St.  Cassian 
and  Hallstadt  of  the  Austrian  Alps.  Directly  overlying  the  upper- 
most Star  Peak  quartzite  is  a  limestone  carrying  Lower  Jurassic  or 
Liassic  forms,  and  succeeded  upward  by  an  immense  series  of  argil- 
lites  of  unknown  thickness. 

Tonto  shale  and  sandstone. — The  name  Tonto  was  applied  by  Mr. 
G.  K.  Gilbert «  in  1874  to  a  series  of  sandstones  and  shales  lying 
l3etween  the  subjacent  granite  and  the  superjacent  limestones  wJiich 
occur  at  the  mouth  of  the  Grand  Canyon  in  Arizona.  He  considers 
the  formation  of  Primordial  age,  and  it  has  been  since  found  to  con- 
tain an  Upper  Cambrian  fauna. ^ 

Truckee  formation. — Mr.  King«  proposed  the  name  Pah-Ute  Lake 
for  a  fresh-water  Miocene  lake,  which  is  regarded  as  extending  from 
the  region  of  the  Columbia  River,  and  perhaps  still  farther  north,  far 
south  through  Oregon  and  Nevada  into  California.  To  the  beds  of 
this  lake  in  the  fortieth  parallel  area  lie  gave  the  name  of  Truckee 
Miocene.  They  are  made  up  of  150  feet  or  less  of  detrital  rocks  and 
gritty  sandstones,  with  some  conglomerate.  Above  these  lie  about 
250  feet  of  palagonite  tuff.  Above  this  is  250  to  300  feet  and  more  of 
infusorial  silica,  followed  by  120  feet  of  detrital  sandy  rocks,  contain- 
ing also  infusorial  silica.  Above  these  comes  60  feet  of  fresh-water 
limestone,  which  is  succeeded  upward  by  250  feet  of  detrital  grits; 
and  the  latter  give  away  to  an  enormous  formation  of  volcanic  tuffs. 
In  Nevada  the  thickness  of  these  volcanic  muds  is  2,000  or  3,000  feet; 
in  Oregon  it  is  even  more. 

a  Third  Ann.  Rept.  U.  S.  Geol.  Sui-vey,  p.  355. 

b  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.  346. 

c  Bull.  Washington  Philos.  Soc,  Vol.  I,  p.  109. 

d  C.  D.  Walcott,  Bull.  U.  S.  Geol.  Survey  No.  81,  p.  245. 

e  Op,  cit.,  p.  454. 


gptJRR.]  DESCEIPTIONS    OF    FOEMATIONS.  23 

Unkar  formation. — This  has  alreadj-  been  mentioned,  under  the 
headings  Grand  Canyon  and  Chuar,  as  the  lowest  division  of  the 
Grand  Canyon  group  of  the  Algonkian  in  the  Grand  Canyon  section. 
It  is  overlain  conformably  by  the  Chuar,  and  separated  below  by  a 
great  unconformity  from  the  Vishnu  series. 

Wasatch  limestone. — The  term  was  applied  by  King"  to  an  enor- 
mous bodj^  of  limestone  seen  in  the  Wasatch  and  farther  west,  but 
not  to  the  east.  He  describes  it  as  a  single  body  of  limestone  about 
7,000  feet  in  thickness,  holding  its  enormous  volume  with  remarkable 
evenness  wherever  observed  over  Utah  and  Nevada.  It  is  underlain 
by  the  Ogden  quartzite,  from  which  it  is  lithologically  sharply  distin- 
guished. Above,  it  passes  into  the  great  Weber  quartzite,  but  there 
is  an  alternation  of  sandstone  and  limestone  beds  at  this  transition 
and  the  thickness  of  these  intercalated  beds  is  very  variable,  reach- 
ing sometimes  about  1,000  feet. 

The  lower  1,400  feet  of  the  Wasatch  limestone  was  regarded  as 
Devonian.  Above  this  is  300  or  400  feet  of  dark,  heavy  limestones 
carrying  fossils  resembling  those  of  the  Waverly  group,  but  which 
perhaps  are  closer  to  the  Devonian.  Directly  above  these  are  400  or 
500  feet  of  dark  beds  carrying  Lower  Carboniferous  fauna,  and  above 
these  the  upper  4,500  feet  of  the  limestone  is  characterized  by  abun- 
dant Coal  Measures  fossils. 

The  term  Wasatch  was  not  retained  in  the  Eureka  section,^  the 
Devonian  and  Carboniferous  being  subdivided  into  various  forma- 
tions. However,  these  lithologic  subdivisions  are  not  readily  recog- 
nizable at  many  other  points  in  Nevada,  and  the  old  term  is  often 
convenient. 

Weber  conglomerate. — Mr.  King^  described  the  Weber  quartzite  as 
a  body  of  indurated  sandstone  and  quartzite  carrying  occasional 
sheets  of  conglomerate,  interposed  between  two  bodies  of  Coal  Meas- 
ures limestone.  He  described  .it  as  obtaining  a  thickness  of  2,000  feet 
in  the  Wasatch,  8,000  feet  in  the  Oquirrh,  and  probably  more  in 
middle  California.  This  formation  overlies  the  Wasatch  limestone 
and  underlies  the  Upper  Coal  Measures  limestone. 

The  same  formation  was  recognized  by  Mr,  Hague  ^^  at  Eureka, 
where  it  is  underlain  by  the  Lower  Coal  Measures  limestone  and  over- 
lain by  the  Upper  Coal  Measures  limestone.  Its  thickness  at  Eureka, 
however,  is  only  2,000  feet.  Here  it  consists  of  coarse  and  fine  con- 
glomerates, with  angular  fragments  of  chert  and  layers  of  reddish- 
yellow  sandstone. 

White  Pine  shale. — This  term  was  a^jplied  by  Mr.  Hague '^  to  the 

aJJ.  S.  Geol.  Expl.  Fortieth  Par.,  Vol  I,  pp.  335-239. 

6  Arnold  Hague,  Mon.  U.  S.  Geol.  Survey,  Vol.  XX,  p.  13. 

cQp.  cit.,  p.  240. 

dLoc.  cit. 


24  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

uppermost  of  the  lithologic  divisions  of  the  Devonian  in  the  Eureka 
district.  It  consists  of  2,000  feet  of  black  argillaceous  shales,  more 
or  less  arenaceous,  with  intercalations  of  red  and  reddish-brown  friable 
sandstone,  changing  rapidly  with  the  locality.  The  beds  contain 
plant  impressions.  The  formation  is  underlain  by  the  Devonian 
Nevada  limestone  and  overlain  by  the  Carboniferous  Diamond  Peak 
quartzite.  These  lithologic  subdivisions  seem  to  change  rapidly  as 
one  goes  away  from  the  Eureka  district,  and  have  not  often  been 
certainly  identified. 


CHAPTER    T 

RAI^GES   OF   EAST-CENTRAI.  KT5VADA. 

SNAKE    RANGE. 

The  Snake  Range  lies  next  east  of  the  Schell  Creek  Range  and  for 
the  most  part  just  west  of  the  Nevada-Utah  line.  It  is  the  most 
eonspicnous  range  between  the  Wasatch  and  the  Humboldt.  The 
northern  end  of  the  range  has  been  variously  called  the  Deep  Creek 
Mountains  or  the  Ibenpah  Mountains,  while  just  south  of  this  part  of 
the  range  a  transverse  ridge  has  been  called  the  Kern  Mountains;  but 
here  they  will  all  be  included  under  the  general  name  Snake  Range. 
The  range,  as  thus  defined,  extends  from  about  latitude  40°  15'  about 
135  miles  in  a  direction  a  little  west  of  south.  At  its  southern  end  it 
runs  into  a  group  of  irregular  mountains,  probably  in  large  part  vol- 
canic, of  which  certain  portions  go  by  the  name  of  the  Cedar  Moun- 
tains, and  the  Piiion  Mountains  of  Lincoln  County. 

TOPOGRAPHY. 

The  relief  of  the  Snake  Range  is  in  general  great.  The  mountains 
are  divided  into  irregular  ridges  which  are  broken  and  separated  by 
transverse  east- west  gaps.  Bj^  two  such  gaps  the  so-called  Kern 
Mountains  are  separated  from  the  rest  of  the  range,  and  a  similar  but 
lower  gap  occurs  just  north  of  Wheeler  or  Jeff  Davis  Peak.  This 
peak  has  the  highest  elevation  of  any  between  the  Sierra  Nevada  and 
the  Wasatch,  attaining  over  12,000  feet  (PI.  HI,  A).  Directly  south 
of  this  the  mountains  decrease  rapidlj'  in  height  and  pass  into  the  low 
volcanic  peaks  above  mentioned. 

Some  of  the  erosion  forms  are  interesting.  On  the  east  side  of  the 
range,  between  Wheeler  Peak  and  the  Kern  Mountains,  a  number  of 
springs  furnish  continual  streams.  At  the  mouths  of  the  gulches 
from  which  such  streams  flow  the  Pleistocene  wash  which  covers  the 
base  of  the  mountains  has  been  lowered  fully  500  feet  below  the  wash 
on  both  sides,  and  the  stream  flows  through  this  deposit  between 
steep  banks  40  feet  high.  Where  near-by  gulches  which  do  not  con- 
tain any  continual  streams  join  the  same  detrital  apron,  the  reverse 
is  the  case,  the  gulches  being  fronted  by  huge  alluvial  fans  higher 
than  the  rest  of  the  i)lateau. 

Considering  the  gulches  formed  b}^  these  continual  streams  and 
comparing  them  with  the  neighboring  gulches  which  do  not  contain 
springs,   we  find  a  strong  contrast.     Smith   Creek,   for  examj)le,  is 

25 


26  GEOLOGY    OF    JSTEVADA   SOUTH    OF   40TH    PARALLEL.     [buli..208. 

a  spring  flowing  in  the  bottom  of  a  magnificent  narrow  canyon, 
bounded  by  perpendicular  walls  2,000  or  2,500  feet  high.  In  these 
walls  are  a  number  of  large  holes  or  caves  in  the  limestones,  which 
evidently  represent  the  former  courses  of  the  same  spring  that  now 
emerges  in  the  gulch  bottom.  From  the  distribution  of  these  caves  it 
appears  that  the  spring  has  been  flowing  during  all  the  time  that  the 
canyon  has  been  eroding  and  that  its  former  underground  courses 
have  been  exposed  by  the  down  cutting.  The  adjacent  gulches,  which 
do  not  continually  contain  running  water,  have  V-shaped  valleys  with- 
out box  canyons,  and  are  much  shallower. 
In  this  canyon  are  small  working  mines. 

ARCHEAN   ROCKS. 

Howell  found  fragments  of  granite  in  the  wash  which  came  down 
from  Wheeler  Peak,  and  regarded  this  as  Archean,  underlying  the 
undoubtedly  Cambrian  quartzite.  Farther  north,  on  the  east  face  of 
the  mountain,  and  on  the  north  side  of  the  gap  which  runs  trans- 
versely across  the  range  north  of  Wheeler  Peak,- the  writer  found 
abundant  schistose  granite  in  the  drift  and  in  one  locality  in  place. 
Where  it  was  found  in  place  it  seemed  to  lie  beneath  limestones  which 
are  probably  Cambrian,  with  no  intervening  quartzite.  Farther 
north,  also  on  the  eastern  side  of  the  range,  one  finds  continually 
huge  blocks  of  schistose  granite  mingled  with  the  blocks  of  schistose 
Cambrian  quartzite.  Upon  the  north  side  of  the  Kern  Mountains 
granite  is  found  in  contact  with  the  schistose  Cambrian  quartzite  and 
also  with  the  overlying  metamorphic  limestones.  The  central  portion 
of  the  Kern  Mountains  is  made  up  of  this  granite,  with  the  Cambrian 
rocks  on  the  flanks.  A  sjpecimen  examined  microscopically  proved  to 
be  a  biotite-muscovite-granite,  approaching  alaskite.  On  the  borders 
of  the  granitic  mass  are  found  siliceous  granitic  dikes,  which  cut  the 
Cambrian  quartzite-schists.  At  one  locality,  which  is  on  the  south- 
west side  of  Pleasant  Valley  and  near  the  State  line,  is  found  a  broad 
belt  of  confused  alaskite  dikes  showing  a  tendency  to  change  into  a 
muscovite-biotite-granite  on  the  one  hand  and  into  large  quartz  veins 
on  the  other. 

Howell'*  notes  that  at  the  head  of  Deep  Creek,  only  a  few  miles 
north  of  Pleasant  Valley,  the  erosion  of  the  creek  has  laid  bare  gran- 
ite underlying  the  quartzite  and  limestone.  From  here  northward  to 
Uiyabi  Pass,  not  far  from  the  northern  end  of  the  range,  he  notes 
that  the  base  of  the  range  is  granite,  overlain  and  flanked  on  the 
west  by  quartzite  and  limestone. 

From  these  evidences  it  would  seem  that  the  limestones  and  over- 
lying quartzites  which  form  the  base  of  the  stratifled  series  in  the 
Snake  Range,  and  which  will  be  presently  shown  to  be  Cambrian,  are 
ordinarily  underlain  by  granite.     But  in  at  least  one  locality  similar 

"U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.,  Ill,  p.  242. 


U.    S.    GEOLOGICAL  SURVEY 


BULLETIN    NO.    203       PL.    Ill 


A.     JEFF    DAVIS   OR    WHEELER    PEAK,    SNAKE    RANGE,    FROM    ROBINSON'S    RANCH. 


li.      NORTH    END    OF   SCHELL   CREEK    RANGE,    FROM    ANTELOPE    RANG: 
Showing  also  the  Tertiary  and  Pleistocene  valleys  between  the  two  ranges. 


sPURR.]  SNAKE    RANGE.  27 

granitic  rock  is  locally  intrusive  into  the  Cambrian  strata,  and  the 
same  has  been  suspected  in  other  places.  From  the  fact,  however, 
that  the  intrusive  phenomena  are  of  minor  importance,  and  also  from 
the  circumstance  that  where  the  Cambrian  quartzite  is  schistose  the 
underlying  granite  also  shows  signs  of  movement,  the  writer  inclines 
to  the  belief  that  the  granite  as  a  whole  is  really  Archean  and  is  the 
basement  upon  which  the  Cambrian  quartzites  were  laid  down.  So 
thick  a  series  of  quartzites  (amounting  to  several  thousand  feet) 
naturally  suggests  a  granitic  land  mass  as  their  source.  As  regards 
the  occasional  intrusive  phenomena,  it  is  possible  that  these  represent 
occasional  outbursts  of  molten  rock  which  found  its  way  from  the 
lower  and  more  heated  regions  up  through  the  crust  of  hard  Archean 
granite  and  into  the  overljdng  Cambrian,  being  intrusive  into  the 
Upper  Archean  as  well  as  into  the  quartzites,  although  belonging  prac- 
ticallj"  to  the  same  body  as  the  basement  granite.  The  writer  would 
suggest  that  this  explanation  may  ]Dossibly  apply  to  Big  Cottonwood 
Canj^on,  in  the  Wasatch,  near  Salt  Lake  City,  where  the  granite  was 
originally  believed  to  be  Archean,  but  where  later  observers  have 
noted  intrusive  phenomena.* 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

In  the  southern  part  of  the  range,  at  Wheeler  Peak,  there  are  heavy 
quartzites  dipping  in  all  directions,  forming  a  gentle  quaquaversal. 
Howell^  notes  the  same  quartzites  for  some  distance  south  of  the  iDeak, 
overlain  by  heavj^  bluish-gray  limestones.  He  estimates  the  lime- 
stones as  4,000  to  5,000  feet  thick,  and  the  underlying  quartzite  at 
not  less  than  1,000  feet. 

North  of  Wheeler  Peak,  at  the  mining  camp  at  Osceola,  the  writer 
observed  these  quartzites,  and  found  on  the  mountain  just  south  of 
the  camp  about  500  feet  of  pure  white  quartzite  underlain  by  about 
2,000  feet  of  massive  gray  quartzite,  with  some  silvery  slate.  At 
Osceola  there  is  an  east-west  fault  which  brings  together  a  massive 
brown  craggy- weathering  quartzite  on  the  north  side  and  the  silvery 
slate  with  quartzite  bands  on  the  south:  Above  the  quartzite,  one  mile 
east  of  Osceola,  there  is  a  high  bluff  of  dark-blue  frosty  lustered  silice- 
ous limestone  with  indistinct,  probably  organic,  markings,  similar  to 
the  limestones  just  west  of  here,  in  the  Schell  Creek  Range.  About  a 
mile  farther  east  the  slight  westerly  dip  of  the  limestones  brings  up 
the  same  underlying  silvery  slates  as  were  noted  in  the  neighborhood 
of  Osceola  and  also  in  the  Schell  Creek  section  at  the  same  horizon. 
The  limestones  in  the  neighborhood  of  Osceola  were  estimated  at 
1,000  feet  thick,  while  the  slates,  as  exposed  in  the  Schell  Creek  sec- 
tion, were  roughly  estimated  at  from  4,000  to  5,000  feet.     A  short 

oC.  E.  Van  Hise,  Correlation  Papers,  Archean  and  Algonkian:  Bull.  U.  S.  Geol.  Survey  No.  86, 
p.  289. 
&U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  241. 


28  aEOLOGY    Oli'    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.  208. 

distance  farther  east  the  slates  are  underlain  by  300  feet  of  brown 
quartzite  like  that  at  Osceola,  below  which  comes  600  feet  of  gray 
quartzite. 

The  following  observations  have  been  directly  communicated  to  the 
writer  by  Mr.  F.  B.  Weeks,  who  made  an  extended  trip  in  the  Great 
Basin  region  in  the  summer  of  1900: 

A  few  hundred  feet  below  the  summit  of  the  ridge  south  of  Osceola  fossils  were 
found  in  the  limestone  and  have  been  determined  by  Mr.  Walcott  as  Lower 
Cambrian. 

About  8  miles  northeast  of  Osceola  the  center  of  the  range  is  occupied  by  hard 
and  massive  drab  and  blue  limestones,  in  which  fossils  collected  at  two  localities 
have  been  determined  by  Mr.  Walcott  to  be  Middle  Cambrian  forms.  These  Cam- 
brian limestones  are  succeeded  by  Ordovician  limestones. 

We  have,  then,  in  the  neighborhood  of  Osceola  a  section  of  sedimen- 
tary rocks  resting  upon  the  basal  granite  and  consisting  of  at  least  2,500 
feet  of  quartzites,  succeeded  by  a  thickness  of  silvery,  somewhat 
micaceous  slates  of  uncertain  but  iDrobably  considerable  thickness, 
and  these  by  at  least  a  thousand  feet  of  metamorphic  limestones. 
The  section  is  identical  with  that  just  west  of  here,  in  the  Schell  Creek 
Range. 

About  20  to  25  miles  south  of  Wheeler  Peak  Cambrian  limestones, 
overlain  by  Ordovician  limestones,  Avere  also  observed  by  Mr.  Weeks. 

All  along  the  eastern  side  of  the  Snake  Range,  north  of  Wheeler 
Peak,  is  found  the  same  section,  although  the  overlying  silvery  slates 
often  become  more  quartzitic  and  pass  into  quartzite-schists.  Just 
north  of  the  east- west  gap  crossing  the  range  north  of  Wheeler  Peak 
a  series  of  2,500  to  3,000  feet  of  craggy-weathering  brown  or  black 
considerably  altered  limestones,  reticulated  by  many  veins  and  highly 
jointed,  was  gone  through.  In  this  limestone  no  fossils  were  seen,  but 
above  it  is  found  limestone  with  Coal  Measures  fossils.  The  lower 
limestone  is  believed  to  be  in  part  Cambrian,  for  below  it  was  found  a 
belt  of  about  200  feet  of  black  shale,  in  which  a  number  of  fossils 
were  collected,  which  were  determined  by  Mr.  C.  D.  Walcott  to  be 
Cambrian.  Below  this  shale  comes  a  peculiar  50-foot  bed  of  white 
marble,  banded  with  gray,  and  beneath  this  upward  of  1,500  feet  of 
highly  schistose  quartzite,  producing  the  effect  of  a  silvery  slate. 

From  here  north  to  the  transverse  gap  which  cuts  across  the  range 
south  of  the  so-called  Kern  Mountains,  one  finds  almost  continuously 
the  same  quartzite-schists  at  the  bottom  of  the  section,  sometimes 
nearly  approaching  the  condition  of  a  mica-schist.  Above  this  come 
heavy  bedded  limestones,  which  weather  brown,  and  which  carry 
indistinct  and  indeterminable  fossil  remains.  Midway  between  the 
northern  end  of  the  main  portion  of  the  Snake  Range,  south  of  the 
Kern  Mountains,  and  the  Kern  Mountains  themselves,  the  same 
metamorphic  limestone  was  found  in  a  butte. 

From  observations  all  along  this  face  of  the  range  the  thickness  of 
the  metamorphic  limestone  was  estimated  at  about  5,000  feet.    A  spec- 


spuRR.]  SNAKE    EA.NGE.  29 

imen  of  the  limestone  examiued  aj)pe<ired  to  contain  indistinct  traces 
of  organic  forms,  but  was  thoroughly  recrystallized. 

At  the  southeastern  end  of  the  Kern  Mountains  the  same  highly 
altered  limestone  Avas  found.  Farther  northwest,  toward  the  heart  of 
the  mountains,  this  is  underlain  bj^  highl}^  altered  quartzite-schists 
with  an  intercalated  band  of  marble  similar  to  the  section  described 
farther  south.  The  schist  is  cut  by  numerous  dikes  of  siliceous  granitic 
rock,  as  above  described.  Thin  sections  of  the  schist  examined 
proved  that  it  Avas  originally  quartzite,  but  the  more  metamorphosed 
specimens  showed  the  dcA^elopment  of  biotite  and  muscovite  along 
sliding  planes,  producing  a  muscovite-biotite-quartzite-schist. 

In  the  mountains  on  the  north  side  of  Pleasant  Valley  Mr.  Howell"' 
has  noted  that  the  range  is  composed  of  quartzite  overlying  granite 
and  itself  overlain  by  limestone.  He  also  notes  that  there  is  fre- 
quently a  little  shale  between  the  limestone  and  the  quartzite.  At 
Uiyabi  Pass  he  estimated  the  limestone  at  from  3,000  to  5,000  feet. 
He  found  there  onl}^  from  200  to  400  feet  of  quartzite  between  the 
granite  and  the  limestone. 

Along  the  nortli  side  of  Pleasant  Valley,  at  the  base  of  the  Deep 
Creek  Mountains,  the  writer  noted  the  continuation  of  the  altered 
limestones  that  overlie  the  quartzites  and  shales  of  the  Kern  Moun- 
tains. This  limestone  was  traced  nortliAvestward  to  the  gap  though 
which  the  road  runs  northward  to  Deep  Creek.  Immediately  west 
of  here  it  is  replaced  by  less  altered  limestone  carrying  Coal  Meas- 
ures fossils. 

We  have,  therefore,  extending  nearly  the  whole  length  of  the 
Snake  Range,  for  100  miles  at  least,  a  heavy  quartzite  resting  upon  a 
basement  of  granite  and  overlain  by  slates,  which  in  turn  are  overlain 
by  massive  metamorphic  limestones.  The  thickness  of  the  quartzite 
in  the  neighborhood  of  Osceola  was  estimated  at  not  less  than  2,500 
feet,  while  Mr.  Howell  found  only  200  or  400  feet  at  the  northern  end 
of  the  Deep  Creek  Range.  The  thickness  of  the  overljdng  shales  or 
slates  seems  to  be  likewise  small  at  the  northern  end  of  the  range, 
while  in  the  neighborhood  of  Osceola  it  is  considerable,  and  was 
roughly  estimated  by  the  writer,  partly  by  comparison  with  the 
adjacent  Schell  Creek  Range  section,  to  be  4,000  to  5,000  feet.  The 
thickness  of  the  massive  limestones  above  was  estimated  by  Mr. 
Howell  at  Wheeler  Peak  at  from  4,000  to  5,000  feet;  by  the  Avriter,  at  a 
point  some  distance  farther  north,  at  about  5,000  feet;  and  by  Mr, 
Howell  at  Uiyabi  Pass  at  from  3,000  to  5,000  feet.  But  at  the  latter 
locality  Howell  found  Carboniferous  fossils,  so  that  at  least  the  upper 
part  of  the  limestone  here  can  not  be  included  with  the  Cambrian. 

The  whole  section  corresponds  in  its  chief  features  to  the  Cambrian 
section  of  the  Schell  Creek  Range,  the  Highland  Range,  and  the  section 
at  Eureka,  and  the  Cambrian  fossils  found  in  the  shale  horizon  above 

au.  S.  Geol.  Surv.  W.  One  Hundredth  Mer.,  Vol.  in,  p.  242. 


30  GEOLOGY    OF    NEVADA    SOUTH    OF    40TH    PAKALLEL.     [bull. 208 

raeutioned  cojifinus  th(^  correlatiou.     AVe  have  therefore  a  roughly 
estimated  thickness  of  at  least  12,500  feet  of  Cambrian  in  this  range. 

SILURIAN. 

On  the  road  which  runs  east  from  Osceola  there  was  observed  a 
hard  Avhite  quartzite  about  400  feet  thick,  which  was  recognized  in 
the  field  as  similar  in  every  respect  to  the  Silurian  Eureka  quartzite 
of  the  Eureka  section. 

Northeast  of  this  locality,  about  4  miles  north  of  Robinson's 
ranch  (PI.  IV,  A),  a  compact  conglomerate,  which  Avill  presently  be 
described  as  probabl}'  Mesozoic  or  T(U"tiary,  contains  large  quanti- 
ties of  similar  white  quartzite,  together  with  limestone  fragments. 
From  some  of  the  limestone  fragments  the  following  Ordovician 
(Lower  Silurian)  fossils  were  obtained  and  identified  by  Prof,  E.  O. 
Ulrich: 

L'eperditia  fabtilites  Conrad,  variety. 
Isoclillina,  sp.  iindet. 
Lophospira.  sp.  cf.  L.  bicincta  Hall. 
Fragments  of  an  Orthis  near  Tricenaria. 

These  conglomerates  pass  laterally  into  limestones  and  white 
Quartzites,  whence  they  are  derived.  The  Leperditia  above  men- 
tioned is  found  in  the  Pogonip  terrane  at  Eureka,  so  that  the  lime- 
stone here  is  very  likely  of  the  same  horizon.  This  also  strengthens 
the  previous  tentative  assignment  of  the  quartzite  to  the  Silurian. 

Eight  miles  northeast  of  Osceola,  in  the  center  of  the  range,  Mr. 
F.  B.  Weeks «  observed,  overlying  Cambrian  limestones,  a  different 
series  of  purple,  drab,  and  white  limestones,  in  which  the  following 
Ordovician  fossils  were  found  (determined  by  Professor  Ulrich) : 

Fragments  of  crinold  column.s. 

Orthis  (cf.  lonensis  and  holstoni). 

Dalmanella  (cf.  testudinaria) . 

Dalmanella  (cf .  emacerata) . 

Dalmanella  (cf.  perveta  and  pogonipensis). 

Bracliiopod  of  tmdetermined  relations. 

Maclurea. 

Eccyliopterns  (near  owenanns  (H.  &  W.)  Ulr.). 

Helicotoma  sp.  imdet. 

Lophospira? 

Cyrtoceras  ?  (very  small). 

Related  to  Serpulites  dissolutus  Billings. 

Asaphus — fragments.     (1) 

AsapluTs.  (2)  ' 

Asaphus  sp.  nndet.         (3) 

Asaphtis  (cf.  curiosus).(4) 

Bathyurns  sp.  nndet. 

Cyphaspis  ?  sp.  undet. 

Two  nndet.  trilobites. 

Illsenus  (cf.  americanns  Billings). 

Amphion  (near  salteri  Billings). 

Amphion  nevadensis  Walcott. 


a  Personal  communication  to  the  writer. 


fi ;,  J 


A  •' 


'^i'h 


SPUHR.]  SNAKE    RANGE.  31 

Mr.  Weeks  states  that  about  20  to  25  miles  south  of  Wheeler  Peak, 
in  the  bold  escarpment  1,500  to  2,000  feet  in  height  which  faces  Spring 
Valley,  the  Ordovician  limestones  abut  against  the  Cambrian  with  a 
very  high  angle  of  dip.  In  this  series  the  following  fossils,  deter- 
mined by  Professor  Ulrich,  have  been  collected: 

First  lot. 

OrtMs  (near  tricenaria) . 

Or  this  (?  type  of  plicatella). 

Orthis  (cf.  bellarugosa) . 

Orthis  n.  sp.  (near  O.  holstoni  Safford). 

Dalmanella  (type  of  testudinaria). 

Dalmanella  (type  of  perveta) . 

Dalmanella. 

Hormotoma  (near  gracilis). 

Leperditia  bivia  White. 

Leperditella  sp. 

Leperditella  ?  sp. 

Sehmidtella  n.  sp.  (near  crassiniarginata). 

Bathynrus  (?  Dikellocephalus) .     Occurs  elsewhere. 

Bathynrus. 

Aniijhion. 

Asaphtis. 

Asaphtis. 

Asaphus  ?  curiosus  (Billings)  Walcott. 

Second  lot. 

Fragments  of  large  cystidean  or  Carabocrinns. 

Orthis  tricenaria-costalis. 

Orthis  pogonipensis  ? 

Orthis  n.  sp.  (near  O.  holstoni  Safford). 

Eccyliopterus— fragment. 

Endoceras  of  new  type. 

Leperditia  bivia  White. 

Leperditia  n.  sp.  (near  bivia  and  fabnlites). 

Leperditia  n.  sp.  (semipunctate). 

Sehmidtella  n.  sp. 

lUaenus  sp.  (?Thaleops). 

Amphion  nevadensis  Walcott. 

Bathyurns  ?  n.  sp.     (Occurs  at  many  localities.) 

These  fossils  are  types  that  were  found  by  Mr.  Walcott  in  the 
Lower  PogoniiD  (Ordovician)  at  Eureka,  and  it  is  not  probable  that 
an  erosion  interval  of  much  importance  occurs  at  this  horizon. 

The  Carboniferous  strata  lie  unconformably  upon  the  Ordovician 
in  nearly  horizontal  position,  and  form  the  remaining  portion  of  the 
Snake  Range.  Between  the  Ordovician  and  the  Carboniferous  there 
is  a  great  interval  of  nondeposition,  since  the  Eureka  quartzite,  the 
Lone  Mountain  limestone  of  the  Silurian,  and  the  whole  of  the 
Devonian  as  exposed  at  Eureka,  are  wanting  in  this  section. 


32  GEOLOGY    OF    T^TEVADA  SOUTH    OF    lOTH    PARALLEL,     [bull. 208. 

CARBONIFEROUS. 

Mr.  F.  B.  Weeks"  reports  that  near  the  southern  end  of  the  Snake 
Range  the  Lower  Silurian  (Pogonip)  i-ocks  are  directly  overlain  hy 
Carboniferous  limestones.  There  is  here  a  gap  in  the  Paleozoic  sec- 
tion. The  upper  formations  of  the  Silurian  as  exposed  at  Eureka 
(the  Eureka  quartzite  and  the  Lone  Mountain  limestone)  are  wanting, 
as  well  as  the  whole  Devonian  section  (8,000  feet  thick  at  Eureka). 
In  a  low  pass  near  the  southern  end  of  the  Snake  Range  Carbonifer- 
ous fossils  were  found,  which  were  determined  by  Dr.  Girty  as  con- 
taining species  of  ZaphrenUs,  Syringopora,  and  Reticularia. 

In  the  section  across  the  range  eastward  from  Osceola,  and  just 
north  of  Wheeler  Peak,  the  Cambrian  rocks  are  succeeded  to  the 
east  by  a  conglomerate  made  up  chiefly  of  the  peculiar  metamorphic 
Cambrian  limestones,  and  also  containing  pebbles  of  the  quartzite 
and  calcite  veins  which  these  limestones  hold.  Between  this  locality 
and  the  next  outcrop  to  the  west  (which  consists  of  Cambrian  quartz- 
ite and  limestones),  there  is  a  gap  of  a  few  miles,  covered  by  a  drift 
in  which  no  rock  outcrops  were  observed.  Succeeding  this  on  the 
east  is  dark-gray,  somewhat  fetid,  calcite-veined  limestone,  which  is 
very  f ossiliferous.  This  locality  yielded  the  following  tipper  Carbon- 
iferous fossils,  which  were  determined  by  Dr.  George  H.  Girty: 

.  Fisttilipora  ?  sp. 
Producttis  n.  sp. 
Prodiictus  sp. 
Marginifera  splendens. 
Spirifer  boonensis. 
Ambocoelia  planiconvexa. 
Seminula  subtilita. 

This  is  lithologically  the  same  rock  as  the  Upper  Carboniferous  on 
the  west  side  of  the  Schell  Creek  Range,  where  it  also  abuts  against 
the  Cambrian. 

This  f ossiliferous  bed  is  succeeded  farther  east  by  similar  limestcmes 
and  by  beds  of  ferriferous  quartzite.  After  about  three-quarters  of  a 
mile  there  comes  in  about  400  feet  of  hard  white  quartzite,  which  is 
supposed  to  be  Silurian.^  The  diij'of  this  flattens  so  that  it  forms  the 
outcrops  and  tlie  tops  of  the  hills  for  a  half  mile  east.  Then  comes 
in,  farther  east,  conglomerate  made  up  of  limestone  fragments  in  a 
reddish,  finely  triturated  matrix.  The  fragments  yielded  the  follow- 
ing Upper  Carboniferous  fossils,  which  were  identified  by  Dr.  George 
H.  Girty: 

Productus  prattenianiis. 
Productus  ijortlockianiis'? 
Marginifera  splendens. 
Spirifer  camerattis. 
Seminula  mira? 

a  Personal  comraunication  to  the  writer. 
&Seep.  30. 


SPURR]  SNAKE    EANGE.  33 

Proceeding  northward  from  this  point  along  the  eastern  face  of  the 
mountains,  there  was  found,  about  4  miles  north  of  Robinson's  ranch, 
a  compact  red  conglomerate,  made  up  mostly  of  white  quartzite  and 
crystalline  limestone  full  of  calcite  veins.  The  limestone  fragments 
yielded  the  following  Ordovician  (Lower  Silurian)  fossils,  which  were 
identified  by  Dr.  George  II.  Girtj^:  Fragments  of  Ortliis  sp.  and 
Leperditia  hi  via. 

From  another  fragment  the  following  Upper  Carboniferous  fossils 
rere  obtained:  Rhomhopora?  sp.  and  lamellibranch  fragments. 

The  angular  shape  of  these  fragments  proves  a  shore  formation. 
TT^o  hundred  yards  north  the  conglomerate  passes  laterally  and 
rapidlj^  into  the  solid  rocks  from  which  it  is  derived — black,  dark- 
blue,  iind  gray  limestones,  thoroughly  seamed  and  crushed,  and  white 
quartzite,  having  nearlj^  the  same  attitude  as  the  conglomerates.  The 
solid  limestone  carries  fossils  like  those  in  the  conglomerate.  Follow- 
ing the  section  northward,  one  passes  through  2,500  or  3,000  feet  of 
limestone  to  a  belt  of  black  shale  in  which  Cambrian  fossils  were 
found,  as  determined  by  Mr.  C.  D.  Walcott. 

From  here  northward  as-  far  as  Pleasant  Vallej^  no  Carboniferous 
fossils  were  found.  On  the  north  side  of  Pleasant  Valley  the  meta- 
morphic  limestones,  which  have  been  referred  to  the  Cambrian,  are 
succeeded  to  the  west,  near  the  gap  where  the  road  to  Deep  Creek 
runs,  by  comparatively  unaltered  although  calcite- veined  limestones, 
which  carry  the  following  Upper  Carboniferous  fossils,  as  determined 
b}^  Dr.  George  H.  Girty: 

Romingeria?  sp. 
Fenestella  sp. 
Prodtictns  pratteniantis. 
Semintila  mira? 
Piignax  rocky montanus. 
Dielasma?  sp.  ~ 

Edmondia?  sp. 
Pleurotomaria  sp. 
Bellerophon  crassus? 

Farther  north,  at  Uiyabi  Pass,  near  the  northern  end  of  the  range, 
Mr.  Howell  found  a  few  fossils,  among  them  Fusuliiia  cylindrioa,  which 
indicate  Carboniferous  age.  These  fossils  were  found  in  Carbonifer- 
ous limestone  which  lies  above  the  Cambrian  quartzite,  and  probably 
in  the  upper  part  of  the  limestone,  the  lower  part  being  presumably 
Cambrian.*  This  limestone,  according  to  Mr.  Howell,*  is  about  4,000 
or  5,000  feet  thick. 

MESOZOIC   OR   TERTIARY. 

As  described  above,  there  was  found  on  the  road  leading  east  from 
Osceola   a  folded  conglomei"ate  made   uj)  of  coarse  limestone  frag- 

o  See  p.  29.  b  u.  S.  Geog.  Surv.W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  243. 

Bull.  208—03 3 


84  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL.     [bult..208, 

ments  carrying  Upper  Carboniferous  fossils  and  evidently  derived 
from  immediately  adjacent  Upper  Carboniferous  strata.  This  con- 
glomerate may  be  part  of  a  series  which  was  examined  for  4  miles 
farther  east,  and  seems  to  consist  mostly  of  gray  sandstones.  The 
sandstones  are  tilted  toward  the  west,  sometimes  at  angles  of  45°,  but 
in  one  place  seem  unconformable  with  a  knob  of  underljdng  lime- 
stone. In  the  mountains  a  few  miles  north  of  Robinson's  ranch,  as 
before  noted,  there  was  found  a  compact  red  shore  conglomerate, 
composed  of  limestone  fragments  carrying  Ordovician  and  Upper 
Carboniferous  fossils.  This  is  100  feet  thick,  and  below  it  comes  50 
feet  of  consolidated  black  limestone  talus;  below  the  talus  is  again 
500  feet  of  reddish  conglomerate.  This  series  dips  45°  to  the  Avest, 
but  200  yards  farther  north  it  seems  to  pass  laterally  into  the  solid 
rocks  from  which  it  is  derived. 

It  thus  appears  that  above  the  Upper  Carboniferous  limestone,  and 
separated  from  it  by  a  distinct  erosion  interval,  if  not  by  an  uncon- 
formity, is  a  thick  series  of  gray  sandstones  and  limestone  conglomer- 
ates. We  have  no  means  of  determining  the  age  of  these  rocks. 
In  its  ijhysical  characters  the  series  corresponds  roughly  to  the  Trias- 
sic  described  in  the  Wasatch  and  eastward  by  Mr.  King."  It  may 
also  be  possibly  Eocene.^ 

PLIOCENE. 

At  the  southeastern  end  of  Pleasant  Vallej^  is  a  considerable  area  of 
level-topped  hills,  which  rise  about  1,500  feet  above  the  valley,  and  are 
symmetrically  eroded.  They  are  composed  of  horizontal,  slightly  con- 
vsolidated  sands,  with  ledges  of  conglomerates.  At  the  base  of  the 
series  the  material  is  coarse  and  little  arranged. 

Just  north  of  here,  on  the  west  side  of  Deep  Creek  Valle}^,  Mr. 
Emmons^  has  described  beds  of  fine  sand  and  marls,  with  some  gravel 
conglomerate,  and  notes  that  they  have  a  general  lithologic  resem- 
blance to  the  Humboldt  Pliocene. 

The  Pleasant  Valley  strata  also  correspond  in  general  appearance 
to  the  supposedly  Pliocene  sands  and  gravels  which  are  found  over  so 
large  a  part  of  Nevada.  They  are  far  above  the  shore  of  Lake  Bonne- 
ville, as  indicated  b}^  Mr.  Gilbert, ^^  and  therefore  appear  to  belong  to 
a  body  of  water  more  ancient  and  probably  more  extensive  than  the 
Pleistocene  lake 

PLEISTOCENE. 

Mr.  Emmons*^  noted  at  the  northern  end  of  the  Deep  Creek  (or 
Ibenpah)  Range  the  terraces  of  a  former  lake,  of  which  the  highest  was 

«U.  S.  Geol.  Expl.  Fortieth  Par  ,  Vol.  I,  pp.  260,  266,  344. 

fclbid.,  p.  375. 

oldem,  Vol.  II,  p.  475. 

(^'Mon.  U  S.  Geol.  Survey  Vol.  I,  map. 

t'Op  cit.,  p.  473. 


SPURR.]  SNA.KE    RANGE.  85 

about  800  feet  above  the  desert  level.  This  is  perhaps  one  of  the 
terraces  of  the  Pleistocene  Lake  Bonneville,  afterwards  described  by 
Mr.  Gilbert. 

IGNEOUS   ROCKS. 


At  the  southeastern  end  of  Pleasant  Valley  occurs  a  series  of  small 
biittes  of  hornblende-andesite.  On  the  west  end  of  this  valley  a  mod- 
erately large  area  at  the  base  of  the  mountains  is  of  augite-aleutite. 

dike;  rocks. 

Along  the  north  side  of  the  Kern  Mountains,  in  Pleasant  Valley, 
many  acid  dike  rocks,  A^arying  from  siliceous  alaskite  to  muscovite- 
biotite-granite,  were  found  cutting  the  Cambrian  quartzites  and 
limestone.  Associated  with  these  dike  rocks  are  abundant  quartz 
veins.  It  is  believed  that  these  dikes  have  some  connection  with  the 
probable  Archean  granite  which  underlies  the  quartzites.  A  specimen 
of  this  granite,  taken  a  few  miles  west  of  the  dikes,  proved  to  be 
biotite-muscovite-granite. 

STRUCTURE. 


The  general  structure  of  the  Snake  Range,  between  Wheeler  Peak 
and  the  Kern  Mountains,  appears  to  be  anticlinal,  although  the  rocks 
are  mostly  worn  away  from  the  eastern  limb.  The  axis  of  the  fold 
runs  along  the  east  side  of  the  mountains  and  is  marked  by  a  north- 
south  depression,  Avith  high  hills  to  the  east  and  the  bulk  of  the 
range  to  the  west.  The  general  dip  on  both  sides  of  the  axis  is  per- 
haps not  more  than  20°,  although  it  increases  locallj^  to  45°  and  even 
more. 

In  the  neighborhood  of  Wheeler  Peak,  also,  the  rocks  form  a 
gentle  anticline.  There  is  also  cross  folding,  with  an  east-west  axis, 
so  that  the  peak  occupies  the  center  of  a  quaquaversal.  A  short  dis- 
tance south  of  the  peak  the  Avestern  half  of  the  princijjal  north-south 
striking  anticline  is  removed,  leaving  the  ridge  monoclinal.'* 

At  the  northern  end  of  the  range  Mr.  HoAvell  *  noted  that  the  struc- 
ture of  the  range  is  anticlinal  at  Uiyabi  Pass,  but  from  there  to 
Pleasant  Valley  it  is  apparently  monoclinal,  only  one  limb  of  the  anti- 
cline being  exposed. 

The  Kern  Mountains,  south  of  Pleasant  Valley,  appear  to  consist 
of  an  anticlinal  fold,  Avith  northwest- southeast  axis  transverse  to  the 
general  trend  of  folding 

FAULTS. 

Mr.  Howell  *  noted  a  cross  fault  running  east  and  west  about  4  or  6 
miles  north  of  Wheeler  Peak,  having   a   doAvnthroAv  to  the  south. 

«U.  S  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  2a.  bibid. 


36  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

The  writer  recognized  this  fault,  and  4  or  5  miles  north  of  it  a  parallel 
fault,  which  seems  also  to  have  been  downthrown  to  the  south. 

Mr.  Weeks'^*  states  that  about  10  miles  northeast  of  Osceola,  in  the 
central  part  of  the  range,  the  Cambrian  limestones  are  broken  by 
numerous  faults  which  strike  northwest  and  southeast.  The  massive 
blue  limestones  which  form  the  upper  part  of  the  series  are  repeated 
several  times  by  small  faults  of  200  to  300  feet  throw.  The  general  dip 
of  the  Cambrian  series  is  to  the  north-northwest,  and  the  dip  of  the 
Ordovician  to  the  east-northeast.  There  appears  to  have  been  an 
upthrust  of  the  Cambrian  which  has  brought  the  successive  limestone 
beds  of  the  series  in  juxtaposition  with  the  Ordovician.  The  existence 
of  a  heavy  fault  between  the  Cambrian  and  Ordovician  is  clearly  seen 
in  the  southern  portion  of  the  Snake  Range.  ^ 

On  the  north  side  of  the  Kern  Mountains  a  belt  of  quartz  veins  and 
siliceous  granitic  dike  rocks,  running  northwest  along  the  base  of  the 
mountains,  appears  to  be  along  a  fault  zone.  On  the  north  side  is  the 
crystalline  nearly  black  Cambrian  limestone,  while  on  the  south  side 
come  schists  which  represent  the  top  of  the  underlying  Cambrian 
quartzite.  The  vertical  separation  of  the  fault  is  probablj^  at  least 
several  hundred  feet. 

ORES. 

At  Osceola,  just  north  of  Wheeler  Peak,  the  Cambrian  quartzites 
and  slates  carry  gold.  Considerable  placer  and  some  vein  gold  has 
been  taken  from  this  district. 

On  the  east  side  of  the  range  there  are  small  mines  and  prospects 
in  a  number  of  places.  In  some  localities  the  coincidence  of  mineral- 
ization with  the  presence  of  a  spring  flowing  in  a  box  canyon  leads  to 
the  hypothesis  that  it  was  these  same  waters  which  formerly  brought 
about  the  ore  deposition.  Along  the  walls  of  such  canyons,  high 
above  the  present  bed,  ancient  water  channels  in  the  limestone  rock 
show  that  the  spring  has  existed  since  near  the  time  when  the  erosion 
of  the  canyon  began. 

CEDAR  RANGE  AND   CLOVER   VALLEY  MOUNTAINS. 

The  Cedar  Range  consists  of  broad,  irregular,  often  mesa-like  hills, 
lying  south  of  the  Snake  Range  and  northeast  of  Pioche.  Southward 
from  the  Cedar  Range,  and  between  it  and  the  Mormon  Range,  there 
lies  to  the  east  of  Meadow  Valley  a  wide  area  of  irregular  mountains 
with  no  definite  system  of  ridges.  In  these  mountains  is  Clover 
Valley,  whence  is  taken  the  name  applied  here. 

The  Cedar  Range  and  the  Clover  Valley  Mountains  may  be  consid- 
ered together  for  purposes  of  description.  They  have  been  partly 
mapped  by  the  Wheeler  survey,^  and  they  have  been  observed  by  the 
writer  at  several  points.  So  far  as  known,  they  consist  entirely  of 
lavas. 

"Personal  communication  to  the  writer. 

bTJ.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  atlas,  geologic  map  No.  58, 


SPURB.]     CEDAE,   CLOVER    VALLEY,   AND    ANTELOPE    RANGES.  37 

The  geology  of  these  mountains  has  not  been  stiTdied  in  detail,  but 
it  is  undoubtedl}'  much  the  same  as  that  described  in  Meadow  Valley 
Canyon,'*  which  is  a  chasm  cut  deep  into  the  same  volcanic  series. 
By  analogy  with  the  rocks  in  this  canyon,  we  may  suppose  that  the 
lavas  of  the  mountains  under  consideration  are  associated  with  de- 
rived sediments  and  that  these  lavas  were  ejected  at  different  periods. 
The  rock  species  will  probably  be  found  to  be  varied,  ranging,  as 
in  Meadow  Valley  Canyon,  from  basal  rhyolite  through  andesites, 
dacites,  latites,  etc.,  to  the  youngest  rhyolite  and  oli vine-basalt. 

ANTELOPE   RANGE. 

The  Antelope  Range  is  a  comparatively  insignificant  group,  about 
30  miles  long,  lying  just  west  of  the  northernmost  portion  of  the 
Snake  Range  (Deep  Creek  Range). 

The  central  part  of  the  range  possesses  a  topography  of  considerable 
relief,  mth  an  especially  bold  face  on  the  east  side  (PI.  IV,  B),  while  on 
the  north  and  on  the  south  ends  the  mountains  give  way  to  low  hills, 
which  finally  disappear  under  the  Pleistocene  detritus  of  the  valleys. 

SEDIMENTARY    ROCKS. 

On  the  eastern  side  of  the  range,  about  3  miles  west  of  Warm 
Springs,  the  Eureka  quartzite  is  exposed  near  the  base  of  the  moun- 
tains, measuring  about  200  feet  in  thickness.  Above  this  come  700  to 
800  feet  of  dark-blue  (probably  Lone  Mountain)  limestone,  having  the 
characteristic  texture  of  this  formation  in  the  Eureka  district.  From 
here  to  the  crest  of  the  range  comes  limestones  (probably  Devonian?) 
consisting  of  dark-blue  and  gray  alternating  bands.  From  the 
extreme  base  of  the  mountains  the  following  fossils  were  found: 
Leperditia'bivia?  White  (very poor);  Dalmanella perveta?  The}^  are 
Ordivician  (Lower  Silurian)  species,  as  determined  hj  Prof.  E.  O. 
Ulrich.  These  fossils  are  characteristic  of  the  Pogonip  horizon  at 
Eureka. 

To  the  north  of  this  locality,  along  the  eastern  face  of  the  moun- 
tains, the  strata  lower  gently,  so  that  the  probable  Lone  Mountain 
and  Nevada  formations  (Upper  Silurian  and  Devonian)  extend  for 
several  miles.  To  the  south  the  strata  rise  and  the  Eureka  quartzite 
passes  half  way  to  the  top  of  the  mountains,  exposing  the  underlying 
Pogonip  (Lower  Silurian)  beds. 

This  belt  of  stratified  rocks  is  cut  off  to  the  north  and  to  the  south 
by  the  volcanic  rocks  which  form  the  greater  part  of  the  range. 

IGNEOUS   ROCKS. 

Along  the  eastern  base  of  the  range,  at  the  foot  of  the  mountains 
composed  of  Paleozoic  strata,  there  is  a  belt  of  foothills  about  3  miles 

a  See  p.  139. 


38  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PAEALLEL.     [bull.208. 

wide  composed  of  lava.  The  same  lava  evidently  underlies  the 
detrital  dei)osits  in  the  whole  valley  between  the  Antelope  Mountains 
and  the  Kern  Mountains  in  the  Snake  Range,  as  is  evidenced  by  occa- 
sional volcanic  buttes  which  project  above  the  Pleistocene  detritus. 
A  few  miles  soutli  of  Warm  Sjjrings,  near  Antelope  Spring-,  the  vol- 
canic rock  invades  the  stratified  rock  in  large  masses  and  soon  forms 
the  whole  of  the  mountains.  From  this  point  along  the  road  which 
leads  from  the  southern  part  of  the  Antelope  Mountains  to  Schellbourne 
and  Cherry  Creek  there  is  nothing  but  the  same  reddish  lava,  and, 
so  far  as  was  seen,  the  lava  seemed  to  extend  northward  to  the  end  of 
the  lange. 

Siiecimens  of  the  lava  collected  at  various  points  throughout  the 
southern  part  of  the  range  prove  to  be  in  general  a  pyroxene-aleutite. 
It  is  essentially^  the  same  rock  which  stretches  across  the  intervening 
valley  to  the  foothills  at  the  western  base  of  the  Snake  Range,  north 
of  the  Kern  Mountains.  The  same  body  of  lava  also  fills  tlie  whole 
valley  between  the  Antelope  Mountains  and  the  northern  part  of  the 
Schell  Creek  Range,  and  extends  to  the  summit  of  this  range. 

The  lava  constituting  the  northern  part  of  the  range  has  been 
described  by  Mr.  Emmons '^  as  rhyolite. 

STRUCTURE. 

Where  the  Paleozoic  rocks  are  exposed  in  the  Antelope  Range  the 
strike  is  in  general  north  and  south  and  the  dip  20°  W.  On  the  west- 
ern borders  of  the  Snake  Range,  directly  east  of  here,  they  have  a 
general  dip  of  15°  E.  The  intervening  valley  is,  therefore,  perhaps 
anticlinal.  The  structure  of  the  stratified  rocks  of  the  Antelope 
Mountains  is  obscured  hy  the  ove-rlying  lavas. 

SCHELL  CREEK   AND   HIGHLAND   RANGES. 

The  Schell  Creek  Range  has  its  northern  end  at  the  fortieth  par- 
allel (PI.  Ill,  B)  and  extends  from  here  southward  about  100  miles  to 
Patterson.  Here  a  slight  gap  separates  it  from  the  Highland  Range, 
which  is  a  direct  continuation  of  it.  The  Highland  Range  extends 
from  Patterson  southward  for  about  80  miles,  when  it  runs  into  the 
Meadow  Valley  Range,  from  which  it  is  separated  by  no  distinct  gap. 
The  Meadow  Valley  Range  will  be  described  later. 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

At  the  northern  end  of  the  Schell  Creek  Range,  in  the  vicinity  of 
Schellbourne,  Mr.  Emmons^  noted  limestones  carrying  Cambrian  fos- 
sils and  overlying  heavy  bodies  of  Cambrian  quartzite.     Mr.  Gilbert^ 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  485. 

6 Ibid.,  p.  486. 

c  U.  S.  Geog.  SiTi-v.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp.  30, 182. 


spuRR.]  SCHELL    CREEK  AND    HIGHLAND    RANGES.  39 

noted  also  Cambrian  fossils  near  Scliellbourne  and  also  botli  north, 
and  south  of  it.  In  Rnbj^  Hill  Canyon,  about  10  miles  south  of  Schell- 
bourne,  quartzites  were  noted  at  the  eastern  base  of  the  ranjj-e,  over- 
lain by  several  thousand  feet  of  limestones.  About  18  or  20  miles 
south  of  Ruby  Hill  and  a  few  miles  south  of  Piermont,  at  Whites 
Peak,  the  quartzites  have  risen  to  the  crest  of  the  range  and  together 
with,  the  associated  schists  display  a  thickness  of  over  11,000  feet. 
Tlie  strata  dip  15°  or  20°  W.,  and  the  overlying  limestone  appears  on 
the  west  flank  of  the  peak.  Southward  from  "Whites  Peak  the  qiiartz- 
ite  gradually  sinks  again,  and  the  crest  of  the  range  is  made  up  of 
the  overlying  limestones. 

The  writer  crossed  the  Schell  Creek  Range  at  Scliellbourne  and 
found  the  eastern  side  composed  of  volcanic  rock.  A  quarter  of  a 
mile  east  of  the  summit  dark-blue  massive  limestone  begins.  Under- 
lying this  limestone,  on  the  west  side  of  the  x>ass,  occurs  dark-blue 
limy  shale,  containing  Cambrian  fossils,  as  determined  by  Mr.  C.  D. 
Walcott. 

This  shale  is  several  hundred  feet  thick  and  contains  a  bed  of  fine- 
grained brown-weathering  quartzite  100  feet  thick.  Similar  fossils 
are  found  above  and  below  the  quartzite.  Beneath  the  shale  comes  a 
well-bedded  limestone. 

In  the  west-facing  scarp  of  the  mountain,  directly  north  of  the  pass 
as  seen  from  Scliellbourne,  the  section  examined  may  be  seen  finely 
exposed.  From  stratigraphic  evidence  the  writer  would  be  inclined 
to  correlate  the  uppermost  limestone  with  tlie  Hamburg  formation  of 
Eureka,  the  shales  with  the  Secret  Canyon  formation,  and  the  lower 
limestones  with  the  Prospect  Mountain  limestone.  An  estimated 
section  of  the  mountains  here  is  as  follows : 

Section  nea.r  Schellhourne. 

Feet. 

Hamburg  limestone 600 

Secret  Canyon  shale _. 600 

Prospect  Mountain  limestone 1, 800 

Neither  the  top  nor  the  bottom  of  the  section  was  observed. 

About  30  miles  south  of  Whites  Peak  and  Piermont  the  writer 
crossed  the  Schell  Creek  Range  along  the  main  road  between  Ely  and 
Osceola.  On  the  east  side  of  the  summit  (which  is  not  high  at  this 
point)  limestone  carrying  abundant  Carboniferous  fossils  appears  to 
abut  against  massive  dark-blue  metamorphosed  limestone,  reticulated 
with  calcite  veins,  and  associated  with  beds  of  marble.  Immediatelj^ 
below  the  metamorphic  limestone  beds  is  a  ferruginous  and  micaceous 
slate  seam,  contorted  and  containing  veins  of  quartzite  and  calcite. 
This  limestone  and  underlying  schistose  slates  constitute  the  whole 
eastern  part  of  the  range. 

1^0  fossils  were  found  at  this  point,  but  the  beds  are  probably  to  be 
correlated  with  the  Cambrian  limestones  and  underlving  shales  at 


40  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull.208. 

Whites  Peak,  at  Ruby  Hill,  and  Schellbourne.  The  succession  and 
the  general  chai'acter  of  the  rocks  are  also  similar  to  those  of  the 
Cambrian  limestones  and  shales  in  the  Highland  Range  in  the  vicin- 
ity of  Pioche  and  in  the  Snake  Range  directly  east  of  here,  in  both  of 
which  localities  Cambrian  fossils  have  been  found. 

On  the  west  side  of  the  range,  north  of  the  locality  just  described 
and  directly  east  of  Ely  in  the  Egan  Range,  the  ridge  which  flanks  the 
main  Schell  Creek  Range  on  the  east  has  along  its  crest  what  appears 
from  a  distance  to  be  the  white  Eureka  quartzite  of  the  Silurian,  dipping 
west  at  a  constant  angle  of  about  30°.  Between  this  ridge  and  the 
main  range  there  is  a  parallel  depression  which  runs  along  the  axis  of 
an  anticline,  for  to  the  east  of  it  the  strata  have  an  easterly  dip  of  from 
20°  to  30°.  On  the  ridge  itself  there  comes  in  below  the  Eureka 
quartzite  strata  resembling  the  thick,  comparativelj'  soft  limestones  of 
the  Pogonip  formation,  and  beneath  this,  in  the  bottom  of  the  valley, 
are  exposed  massive  gray  limestones,  which  are  perhaps  Cambrian. 
These  Cambrian  and  Silurian  rocks  do  not  extend  south  past  the  end  of 
the  ridge  which  forms  the  western  high  limb  of  the  anticline,  but  are 
replaced  to  the  south  ^^y  the  Devonian,  tilie  two  regions  being  appar- 
ently separated  by  a  heavy  east-west  fault. 

Mr.  Howell'*  has  described  the  rocks  at  the  southern  end  of  the 
Schell  Creek  Range.  He  notes  that  at  Patterson  a  heavy  bed  of 
quartzite  is  exposed,  dipping  about  45°  ESE.  A  few  miles  to  the 
north  this  is  covered  conformabl}^  by  bluish-gray  limestone.  IsTo  fos- 
sil remains  sufficient  for  determination  were  found,  but  the  limestone 
was  correlated  on  lithologic  grounds  with  the  su^jposedly  Carbonifer- 
ous limestones  of  the  Snake  Range  and  the  Highland  Range.  Inas- 
much as  at  least  the  southern  portion  of  the  Highland  Range  consists 
of  Cambrian  limestones,  which  were  classed  by  Mr.  Howell  as  Carbon- 
iferous, but  subsequently  definitelj^  determined  as  Cambrian,  and 
since  the  same  Cambrian  series  occurs  in  the  Snake  Range,  it  seems 
likely  that  these  rocks  may  also  be  Cambrian.* 

At  the  north  end  of  the  Highland  Range,  just  south  of  Patterson, 
Mr.  Howell  found  Carboniferous  limestone  well  characterized  by 
fossils. 

At  Bristol,  on  the  west  side  of  the  range,  and  about  30  miles 
south  of  Patterson,  Mr.  Howell  noted  quartzite  at  the  base,  while 
the  whole  upper  portion  was  highly  metamorphic  limestone.  This 
section,  so  far  as  it  goes,  accords  with  the  Cambrian  section  of  the 
southern  end  of  the  range,  as  will  be  mentioned  later. 

Mr.  Walcott ''  noted  on  the  western  side  of  the  range,  at  the  same 
locality  as  just  mentioned,  the  occurrence  of  the  Eureka  quartzite.  It 
is  possible  that  this  is  the  same  quartzite  mentioned  by  Mr.  Howell. 

«U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  HI.  x>  2'i2. 

I)  Subsequent  to  tho  writing  of  this  Mr.  F.  B.  Weeks  collected  Cambrian  fossils  near  Patterson, 
in  these  limestones,  above  the  quartzites. 
e  Bull.  U.S.  Geol.  Survey  No.  30,  p.  36.  • 


SPURR.]  SCHELL    CREEK    AND    HIGHLAND   RANGES.  41 

The  writer  passed  only  a  few  miles  from  Bristol,  proceeding-  from 
Coyote  Spring  over  Stami^ede  Gap,  and  he  also  mapped  the  Silurian 
as  extending  across  the  valley  to  Bristol,  and  indicated  in  liis  notes 
the  probable  occui'rence  of  the  Eureka  quartzite. 

At  Stampede  Gap  the  range,  with  the  exception  of  some  ver}^  low 
foothills  at  the  western  base,  which  will  be  referred  to  later  as  prob- 
ably Devonian  or  Silurian,  is  composed  of  about  800  feet  of  mingled 
limestone  and  slate  overlain  by  about  1,400  feet  of  massive  limestone 
containing  siliceous  beds.  Some  of  these  upper  limestones  carry 
indistinct  and  indeterminable  organic  remains.  A  mottled  structure, 
seeming  to  indicate  the  former  presence  of  coral  remains  in  the  now 
altered  rock,  is  common,  being  the  same  structure  as  observed  in  the 
Cambrian  rocks  of  the  Schell  Creek  Range,  described  above  as  occur- 
ring about  30  miles  south  of  Piermont.  In  the  limestones  at  both 
localities  metainorphism  has  caused  the  same  peculiar  pitted  appear- 
ance which  results  from  the  segregation  of  metamorphic  minerals. 

In  the  Highland  Range,  about  4  miles  south  of  Stampede  Gap  and 
about  the  same  distance  southwest  from  Pioche,  the  entire  range 
appears  to  be  of  Cambrian  strata,  and  Mr.  Walcott"  has  measured 
the  following  section: 

Section  in  High  Ian  d  Range  4  miles  south  of  Stampede  Gaj). 

Feet. 

1 .  Quartzite 350 

2.  Limestone  and  shales,  argillaceous  and  arenaceous 1  1 ,  450 

3.  Massive  limestone 3, 000 

Total 4,800 

The  fossils  which  he  collected  at  various  points  correlated  this  sec- 
tion with  the  Cambrian  at  Eureka,  the  Itasal  quartzite  corresponding 
to  the  Prospect  Mountain  quartzite. 

In  the  Highland  Range,  south  of  Bennetts  Spring,  the  writer  has 
noted  the  probable  continuation  of  the  Cambrian  section  for  a  dis- 
tance of  5  or  6  miles  at  the  very  least,  the  section  being  substantially 
the  same  as  between  Bennetts  Spring  and  Stampede  Gap.  From  the 
eastern  base  of  the  Highland  Range  abundant  quantities  of  brown 
quartzite,  probably  representing  the  basal  Cambrian  quartzite  of  Mr. 
Walcott's  section,  come  down  into  the  vallej^  drift.  This  quartzite  is 
probabh^  overlain  by  the  Cambrian  limestone,  for  the  strata  appear 
horizontal  on  the  east  side  of  the  Highland  Range  throughout  prac- 
tically its  whole  length. 

At  Pioche  Mr.  Howell*  noted  400  feet  of  highly  metamorphic  blue- 
gray  limestone,  and  below  this  about .400  feet  of  shales,  which  yielded 
abundant  Cambrian  fossils.  Below  these  shales  is  an  unknown  thick- 
ness of  quartzite.  He  correlated  this  quartzite  with  the  Cambrian 
quartzites  of  the  Snake  and  Wasatch  ranges.     Mr.  Walcott*  has  also 

«BuU.  U.  S.  Geol.  Survey  No.  30,  p.  34. 

b\J.  S.  Geog.  Sm-v.  W.  One  Hundredth  Mer.,  Vol  III,  p.  242. 


42  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

studied  the  Cambrian  section  at  Pioche  and  finds  a  tliiclvness  of  the 
basal  quartzite  of  1,200  feet  on  the  west  face  of  the  Elj^  Range,  a  few 
miles  to  the  west  of  the  town  of  Pioche.  Mining  operations  have 
thrown  out  large  masses  of  shales  carrying  Cambrian  fossils,  which 
Mr.  Walcott  *  has  described  and  correlated  with  a  bed  of  the  Highland 
Range  section.  Similar  fossils  were  also  collected  at  the  same  locality 
hy  the  writer.  This  horizon  is  well  up  in  the  shaly  limestone  which 
overlies  the  basal  quartzite. 

Three  or  4  miles  southeast  of  Pioche,  along  the  road  to  Panaca, 
what  is  probablj^  tlie  basal  quartzite  is  slightly  exposed,  immediately 
overlain  by  the  shales.  From  these  shales  Mr.  Walcott  collected  a 
number  of  Cambrian  fossils.  The  writer  also  collected  fossils  from 
this  point. 

SILURIAN. 

In  the  western  face  of  the  Schell  Creek  Range,  just  east  of  EI3'  in 
the  Egan  Range,  what  is  perhaps  the  Silurian  Eureka  quartzite 
appears,  forming  the  crest  of  a  minor  ridge,  flanking  to  the  west  the 
main  Schell  Creek  Range.  The  quartzite  dips  to  the  west  about  30" 
and  is  underlain  by  what  appears  to  be  the  Pogonip  formation.  No 
fossils  were  collected. 

The  Silurian  rocks  above  described  are  probably  cut  off  to  the  south 
by  an  east- west  fault,  for  thej^  are  succeeded  bj^  Devonian  strata. 

Mr.  F.  B.  Weeks ^  found,  in  1900,  that,  about  10  miles  nortli  of  the 
road  leading  from  Osceola  to  Ely,  the  Cambrian  beds  on  the  north- 
east are  separated  from  Ordovician  beds  on  the  southwest  b}^  a  heavy 
fault.  In  these  Ordovician  beds  the  following  fossils,  determined  by 
Professor  Ulrich,  were  collected : 

Orthis  (related  to  O.  bellariigosa)-. 

Dalraaiiella  (near  perveta). 

Dalmanella  (near  emacerata). 

Modiolodon  sp.  nndet. 

Ischyrodonta  sp.  tindet. 

Cyrtodonta  ?  sp.  tindet. 

Mackirea  (cf.  subannulata  Walcott). 

Gyronema  (near  semicarinatum). 

Metoptoma  sp.  iindet. 

Endoceras  (1). 

Endoceras  (2). 

Leperditia  (near  fabulites). 

Leperditella. 

Leperditella  (with  ventral  swelling). 

Sclnnidtella  n.  sp.  (near  crassimarginata). 

Aparcliites  sp.  nndet. 

Olenus  ?  sp.  undet.  (1). 

Olenus  ?  sp.  iindet.  (2). 

Asaphns. 

Pygidinm.  sp.  tindet. 

«  Bull.  U.  S.  Geol.  Snrv.  No.  30,  p.  36.  f  Personal  commimication  to  the  writer. 

Blbid.,  pp.  34,  35. 


spuRR]  SCHELL    CREEK    AND    HIGHLAND    EANGES.  43 

Another  lot  was  as  follows: 

Asaphus  (related  to  Megalaspis  belemnuras  White). 

Two  species  of  trilobites  related  to  Symphysurus  goldfussi  Walcott. 

Leperditella  (related  to  L.  inflata). 

Undet.  ostracod  (?  related  to  Octonaria). 

Silurian  rocks  do  not  appear,  so  far  as  yet  observed,  until  the  neigh- 
borhood of  Bristol,  where  the  Eureka  quartzite  Avas  observed  by  Mr. 
Walcott.  The  writer  also  has  observed  probable  Silurian  rocks,  con- 
stituting low  hills,  which  connect  the  Highland  Range,  in  th.e  neigh- 
borhood of  Bristol,  with  the  irregular  ridges  lying  between  the  Egan 
and  Pahroc  ranges. 

Farther  south  Mr.  Walcott "  has  noted  the  Eureka  quartzite  on  the 
west  side  of  the  Highland  Range,  in  a  hill  north  of  the  road  leading 
from  Bennetts  Spring  to  Hiko.    At  this  point  fossils  ai'e  very  abundant. 

DEVONIAN. 

At  the  western  base  of  the  Highland  Range,  at  Stampede  Gap, 
highly  fossiliferous  strata  were  observed,  probably  separated  from  the 
Cambrian  strata  which  form  the  mass  of  the  range  bj^  a  heavy  north- 
south  fault.  No  fossils  were  collected,  but  from  the  stratigraphy  it 
seems  possible  that  these  are  the  continuation  of  rocks  in  the  neigh- 
borhood of  Coyote  Spring,  at  the  northern  end  of  the  Pahroc  Range, 
just  west  from  Stampede  Gap,  which  are  Devonian. 

On  the  western  side  of  the  range,  north  of  the  road  which  crosses 
it  between  Ely  and  Osceola,  the  writer  found  dark-blue  to  gray-blue, 
often  shaly  limestone  filled  with  calcite  seams.  From  one  horizon  in 
this  limestone  he  collected  the  following  Devonian  fossils,  which  were 
determined  by  Dr.  George  H.  Girty:  Stromatoporoid  coral,  Sjjirifer 
utaJiensis,  and  Amhocadia  umbonata. 

These  Devonian  strata  are  apparentl^^  separated  from  Silurian  and 
Cambrian  rocks  farther  north  by  an  east- west  fault. 

CARBONIFEROUS. 

The  western  half  of  the  Schell  Creek  Range,  where  it  was  crossed  qn 
the  road  between  Ely  and  Osceola,  about  20  miles  southeast  of  Ely, 
is  chiefly  composed  of  Carboniferous  rocks.  Thej"  consist  mostly  of 
dark-blue,  gray-blue,  and  often  shaly  limestones,  with  occasional 
brown  quartzite  seams.  Some  of  the  beds  are  semicrystalline.  The 
series  throughout  is  highl}^  fossiliferous. 

Just  after  the  road  enters  the  range  Upper  Carboniferous  fossils 
were  collected.     They  wore  determined  by  Dr.  George  H.  Girty,  as 
follows:    Zaphrentis   sp.,    Productus   sp.,    Spirifer   rockymontanus,  ^ 
Semimda  sp. 

«BuU.  U.  S.  Geol.  Survey  No.  30,  p.  36. 


44  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

A  mile  east  of  the  above-mentioned  locality  the  following  Upper 
Carboniferous  fossils  were  collected : 

Orbiculoidea  missoiiriensis. 

Prodiictiis  infiattis? 

Marginif era  imiricata.  T 

Cleiothyris  orbicularis. 

Seminula  snbtilita.  ' 

Rhombopora  lepidodendroides. 

All  these  Carboniferous  rocks  dij)  to  the  east  20°  or  30°,  and  appar- 
ently abut  directly  against  the  Cambrian  on  the  east. 

Near  the  northern  end  of  the  Highland  Range,  3  or  -4  miles  south  of 
Patterson,  Mr.  Howell'^' has  noted  2,000  feet  of  limestone  containing 
well-marked  Carboniferous  fossils. 

IGNEOUS   ROCKS. 


In  the  vicinity  of  Schellbourne  the  whole  eastern  part  of  the  Schell 
Creek  Range  is  covered  by  basic  lava,  and  this  also  overflows  to  the 
western  part  of  the  range,  covering  up  in  patches  the  stratified  Cam- 
brian rocks.  This  lava  is  in  general  a  pyroxene-aleutite.  According 
to  Mr.  Emmons,*  the  extreme  northern  portion  of  the  range  is  entirely 
covered  by  rhyolite.  In  the  vicinity  of  Schellbourne  the  writer 
found,  underlying  the  basic  lava,  a  few  feet  of  white  biotite-rhj^olite. 

On  the  western  side  of  the  Highland  Range,  5  or  6  miles  south  of  its 
northern  end,  Mr.  Howell '^  has  reported  lava.  Still  farther  south,  at 
Stampede  Gap,  the  writer  observed  a  small  area  of  rhyolite  in  the 
vallej^  at  the  western  base  of  the  mountain. 


Mr.  Gilbert '^^  has  noted  in  Ruby  Hill  Canj'on,  a  few  miles  south  of 
Schellbourne,  siliceous  dikes  cutting  the  Cambrian  limestones. 

STRUCTURE. 


On  the  west  side  of  Schell  Creek  Range,  just  east  of  Ely,  a  conspic- 
uous anticline  was  observed,  trending  parallel  to  the  crest  of  the  main 
range.  The  axis  of  this  anticline  is  occupied  by  a  valle}^,  and  the 
western  limb  is  marked  by  a  minor  north-south  ridge  running  from 
about  the  latitude  of  Ely  northward  to  the  neighborhood  of  Schell- 
bourne, The  rocks  exposed  in  this  anticlinal  fold  are  probably  Silu- 
rian.    To  the  south  the  fold,  and  at  the  same  time  the  ridge  in  which 

aU.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  243. 

b  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  486. 

c  Op.  cit.,  p.  243. 

d\J.  S.  Geog.  Sui-vey  W.  One  Hundredth  Mer.,  Vol.  Ill,  p  31. 


spuRR]  SCHELL    CREEK    AND    HIGHLAND    RANGES.  45 

its  western  limb  is  exhibited,  are  api3arently  cut  off  by  an  east-west 
fault,  while  on  the  north  the  rocks  of  the  fold  pass  under  the  Pleisto- 
cene valley  detritus.  About  10  miles  south  of  the  southern  end  of 
the  minor  ridges  above  mentioned  what  aj)pears  to  be  the  continua- 
tion of  the  same  anticlinal  fold  is  exhibited  in  the  foothills  on  the 
west  side  of  the  range.  Still  farther  south  the  general  strike  of  the 
rocks  changes  from  south  to  soutliAvest,  and  this  anticlinal  fold  prob- 
ably passes  over  into  the  southern  end  of  the  Egan  Range,  Avhere-a 
series  of  folds  was  observed,  one  of  which  is  perhaps  identical  with 
it.  Farther  south  again  there  is  probably  another  synclinal  fold, 
whicli  also  passes  over  into  the  Egan  Range  on  account  of  its  south- 
westerly strike.  This  is  probably  followed  by  an  anticlinal  fold,  such 
as  HowelP'  has  described,  at  the  extreme  southern  end  of  the  range, 
where  the  rocks  dip  east-southeast.  Still  farther  south  the  several 
folds  which  are  found  in  the  ridges  forming  the  southern  extremity 
of  the  Egan  Range  are  probably  continuous  across  the  intervening 
valley  to  the  Highland  Range. 

The  Cambrian  rocks,  which  form  the  greater  iDart  of  the  eastern 
portion  of  the  Schell  Creek  and  Highland  ranges,  are  also  folded. 
At  Schellbourne  the  rocks  seemed  to  the  writer  to  dip  in  general  to 
the  east,  although  the  attitude  could  not  be  certainly  made  out. 
Farther  south,  at  Whites  Peak,  Mr.  Gilbert^  found  the  Cambrian 
rocks  dipping  to  the  west  at  an  angle  of  about  20°.  Still  farther 
south,  Avhere  the  writer  observed  the  Cambrian  rocks  in  crossing  the 
range  between  Ely  and  Osceola,  he  found  the  folding  complicated 
and  the  faulting  considerable. 

In  the  Highland  Range  the  folds  in  the  Cambrian  rocks  appear  to 
be  gentle  and  of  no  great  extent.  Those  that  were  observed  Avere 
mostly  transverse  to  the  range,  and  in  general  the  disposition  of  the 
horizons  did  not  vary  greatlj^  from  what  they  would  have  been  had 
they  been  horizontal. 

FAULTING. 

Although  no  careful  examination  has  been  made,  the  stratigraphy 
indicates  the  existence  of  important  faults  in  the  Schell  Creek  and 
Highland  ranges.  These  probably  belong  to  two  chief  systems — one 
north  and  south  and  one  east  and  west.  On  the  road  which  crosses 
the  Schell  Creek  Range  between  Ely  in  the  Egan  Range  and  Osceola 
in  the  Snake  Range  the  whole  rock  series  dips  to  the  east.  The  east- 
ern half  of  the  range  is  comj)osed  of  Upper  Carboniferous  limestones 
carr3ing  abundant  fossils,  while  the  western  is  composed  of  metamor- 
phic  limestones  underlain  by  schistose  mica-slates.  The  character  of 
these  later  rocks,  together  with  the  succession,  enables  one  to  correlate 
them  with  the  Cambrian  rocks  found  in  the  same  range  just  north  of 

a  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  342. 
6Ibid.,  p.  31. 


46  GEOLOGY    OB'    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

here  and  also  in  the  Highland  and  Snake  ranges.  This  implies 
either  an  enormous  fault  or  a  great  erosion  gap. 

Opposite  Stampede  Gap  the  writer  crossed  the  valley  which  lies  on 
the  west  of  the  range  from  a  district  where  there  ai^e  abundant  expo- 
sures of  fossiliferons  Devonian  and  Silurian  rocks.  At  the  western 
base  of  the  range  he  noted  in  the  foothills  fossiliferons  strata,  appar- 
ently belonging  to  the  same  series,  from  which,  however,  he  collected 
no  fossil  remains.  Proceeding  farther  west  he  found  the  whole  moun- 
tain made  up  of  altered  massive  limestones,  with  intercalated  shales 
and  schistose  slates,  which  belong  to  the  Cambrian.  A  few  miles 
north  of  Stampede  Gap,  at  Bristol,  Mr.  Walcott  found  the  Eureka 
quartzite  of  the  Silurian  at  the  western  base  of  the  mountains,  and 
the  same  formation  about  15  miles  south  of  Stampede  Gap  on  the  road 
from  Bennetts  Spring  to  Hiko.  Both  these  places  occupy  the  same 
relative  position  at  the  Avestern  base  of  the  range.  Between  these 
Silurian  foothills  and  the  Cambrian  rocks  of  the  main  range  there 
appears  to  be  a  great  break,  bringing  about  juxtaposition  of  strata 
which  in  their  normal  stratigraphic  succession  are  separated  by  nearly 
2  miles  of  intervening  sediments.  This  is  believed  to  be  the  same 
break  as  that  previously  noted  farther  north,  and  it  may  be  either  a 
fault  or  an  erosion  gap. 

An  east-west  fault  ai3pears  to  cut  the  range  transversely  at  a  point 
about  10  miles  southeast  of  Ely  in  the  Egan  Range.  To  the  north 
of  this  line  is  an  anticlinal  fold  which  exposes  probable  Silurian  or 
Cambrian  rocks.  To  the  south  only  the  eastern  limb  of  the  fold  is 
found,  the  ridge  which  represents  the  western  limb  being  cut  off.  On 
the  south  side  the  rocks  carry  Devonian  fossils. 

About  10  miles  north  of  the  road  which  crosses  the  range  between 
Osceola  and  Ely  Mr.  F.  B.  Weeks*  observed,  in  1900,  a  strong  north- 
west fault  marked  by  a  profound  interior  valley.  Cambrian  rocks  on 
the  northeast  side  of  the  fault  are  brought  against  Ordovician  strata 
on  the  north.     The  fault  cuts  across  the  entire  range. 

Mr.  Howell^  noted  a  probable  cross  fault  near  the  north  end  of  the 
Highland  Range.  The  line  of  this  fault  is  continuous  with  a  probable 
fault  line  sketched  by  the  writer  on  the  Egan  Range,  just  to  the  west. 
The  writer  also  saw,  a  few  miles  north  of  this,  what  is  perhaps  a  par- 
allel east- west  fault,  marked  by  a  deep  transverse  valley  in  the  Egan 
Range  and  extending  across  to  the  gap  which  separates  the  Schell 
Creek  Range  from  the  Highland  Range.  The  displacement  of  these 
faults  was  not  measured,  but  is  probably  very  considerable. 

At  Pioche  there  are  a  number  of  intersecting  faults,  some  belonging 
to  a  northwest-southeast  system  and  some  to  a  northeast-southwest 
system.  The  main  fault  observed  by  the  writer  runs  tlirough  the 
south  end  of  the  town,  in  a  northwest  direction.     It  is  marked  bj'-  a 


"Personal  communication  to  the  writer. 

&U.  S.  Geog  Surv.  W.  One  Hundredth  Meridian,  Vol.  Ill,  p.  243 


SPURK.]  EGAN    RANGE.  47 

deep  guleli,  and  has  the  Cambrian  quartzite  on  the  northeast  side  and 
the  Cambrian  shale  and  limestone  on  the  south.  This  fault  has  at 
least  1,000  feet  of  vertical  separation  and  may  have  much  more. 
Other  faults  are  parallel  to  this,  and  there  are  a  number  of  northeast- 
southwest  cross  faults  with  considerable  displacement.  The  effect  of 
these  is  to  cause  a  certain  degree  of  checkering  of  quartzite  and  lime- 
stone. The  northeast  gulch  in  which  Pioche  lies  seems  to  mark  one 
of  these  faults.'* 

EGAN  RANGE. 

The  Egan  Range  is  the  next  important  range  west  of  the  Schell  Creek 
and  Highland  ranges.  Its  north  end  lies  just  north  of  the  fortieth 
parallel  and  is  included  in  the  maps  of  the  Fortieth  Parallel  Survey. 
It  extends  due  southward  nearly  150  miles. 

TOPOGRAPHY. 

;  Throughout  nearly  its  whole  course  the  Egan  Range  consists  of  a 
single  well-defined  central  ridge,  from  which  the  slopes  to  the  valley 
on  both  sides  are  comparatively  steep.  In  the  neighborhood  of  Ely 
the  ridges  are  slightlj^  broken  up,  but  this  is  apparently  due  largely 
to  the  presence  of  igneous  rocks.  At  the  extreme  south  end,  also,  the 
main  range  splits  up  into  several  low  ridges. 

The  range  is  cut  through  at  intervals  by  transverse  valleys  connect- 
ing the  vallej^s  on  either  side  of  the  range  and  very  little  higher  than 
they.  Such  valleys  are  found  at  Egan  Canyon  and  at  Ely.  Near  the 
southern  end  of  the  range  there  are  other  deep  transverse  gaps, 
which,  however,  do  not  cut  clear  down  to  the  level  of  the  vallej^s. 

ARCHEAN   ROCKS. 

Mr.  S.  F.  Emmons  *  has  described  the  rocks  in  an  outlying  ridge  on 
the  east  side  of  the  range,  just  south  of  the  eastern  end  of  Egan 
Canyon.  Here  the  lowest  formation  exposed  is  a  mica-granite,  which 
is  overlain  by  quartzites  and  quartzitic  schists  referred  to  the  Cam- 
brian.    The  granite  is  referred  to  the  Archean. 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

As  above  noted,  Mr.  Emmons  found  overlying  the  granite  at  the 
eastern  end  of  Egan  Canyon  several  thousand  feet  of  quartzites  and 
quartzitic  schists,  together  with  a  50-foot  bed  of  argillite.  These 
quartzites  are  overlain  hy  limestones. 

The  same  locality  was  observed  by  the  writer  from  a  distance,  and 
on  account  of  the  stratigraphy  was  referred  with  little  hesitation  to 

«  These  observations  are  in  accordance  with  those  previously  made  hy  Mr.  Howell  (U.  S.  Geog. 
Surv.  W.  One  Hundreth  Mer.,  Vol.  Ill,  pp.  2,57-361),  as  the  writer  discovered  since  writing  the 
above. 

&U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  488. 


48  GEOLOGY    OF    NEVADA  SOUTH    OF    -lOTH    PARALLEL,     [bull. 208. 

the  Cambrian.  The  rocks  were  not  visited,  but  at  the  base  are  heavy 
beds  dipping  to  the  west  at  an  angle  of  about  30"  and  striking  north 
and  south.  These  massive  beds  resemble  the  Cambrian  quartzite 
and  limestone,  while  above  them  come  more  easily  eroded  limestones, 
which  correspond  in  thickness  and  position  to  the  Silurian  Pogonip 
formation.  Above  the  Pogonip  on  the  east  face  of  tlie  main  ridge 
(which  is  separated  from  tlie  spur  above  mentioned  by  a  trough  of 
erosion)  is  exposed  the  Eureka  quartzite,  which  is  traceable  along 
the  range  for  several  miles  northward.  The  identification  of  this 
Silurian  makes  the  reference  of  the  easterly  rocks  of  the  outlying 
spur  to  the  Cambrian  safe. 

Mr.  F.  B.  Weeks '^^  reports  that  in  the  summit  of  the  range,  about 
10  to  12  miles  south  of  Egan  Canyon,  the  following  Upper  Cambrian 
fossils,  determined  by  Mr.  Walcott,  were  collected: 

Obolus  (Lingulella)  discoidensls  H.  &  W. 
Obolus  (Lingulella)  manticiilus  White. 
Obolus  (Lingulella)  punctatus  Walcott. 
Ophileta? 
Agnostus,  2  sp. 
Ptychoparia,  2  sp. 

Along  the  soutliern  jjart  of  the  Egan  Range  the  west  face,  which 
confronts  the  southern  part  of  Sierra  Valley,  exposes  some  magnificent 
sections  of  strata.  These  also  were  not  visited  any  farther  north  than 
the  vicinity  cf  Adams's  ranch  on  White  River,  near  which  point  they 
were  found  to  be  Devonian.  Farther  north,  however,  a  thick  section 
of  rocks,  striking  northeast  and  dipping  southeast  at  an  average 
angle  of  30",  was  exposed,  and  the  circumstance  that  the  strike  is 
diagonal  to  the  north-south  face  of  the  range  brings  it  about  that 
progressively  lower  beds  are  exjiosed  going  north.  About  2  miles 
north  of  the  vicinity  of  Butterfleld  Spring  what  was  taken  to  be 
Eureka  quartzite  was  seen  at  a  distance;  below  this  occurs  a  great 
thickness  of  more  easily  eroded  limestones,  which  were  referred  to  the 
Pogoni'p  formation;  and  beneath  these  again  massive  limestones, 
which  perhaps  represent  the  Upper  Cambrian.  Only  a  comparatively 
slight  thickness  of  the  latter  limestones  is  exposed,  when  the  dip  of 
the  section  is  reversed  and  becomes  northwest,  so  that  the  section 
begins  to  ascend  toward  the  north. 

SILURIAN. 

Mr.  Emmons*  noted  the  finding  of  Silurian  fossils  in  the  limestone 
in  the  neighborhood  of  Egan  Canyon.  The  writer,  who  crossed  the 
range  at  this  point  from  Cherry  Creek  westerly,  did  not  succeed  in 
finding  any  good  fossils,  but  identified  the  formations  on  lithologic 
and  stratigraphic  grounds  as  notably  belonging  to  the  Pogonip,  the 

"Personal  comnmnicatiou  to  the  writer. 

&U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  488. 


SPUKR.]  EGAN    RANGE.  .49 

Eureka,  and  the  Lone  Mountain  formations  of  the  Silurian  as  exhib- 
ited in  the  Eureka  section.  In  the  easterly  spur  of  the  mountains 
just  south  of  Egan  Canyon,  as  above  noted,  the  whole  thickness  of  the 
Pogonip  strata  is  exposed,  occupjang  a  valley  of  erosion  between  this 
spur  and  the  main  ridge.  On  the  easterly  face  of  the  main  ridge  the 
Eureka  quartzite  is  exposed,  and  may  be  traced  across  Cherry  Creek 
and  still  farther  north.  Above  the  quartzite,  in  ascending  from 
Cherrj^  Creek  westerly,  dark-blue  cr^^stalline  limestones,  similar  litli- 
ologicall}^  to  the  Lone  Mountain  limestones  of  Eureka,  and  carrying 
indistinct  fossils,  were  observed. 

The  probable  exposure  of  the  Eureka  quartzite  on  the  western  face 
of  the  range,  near  its  southern  end,  has  already  been  noted  in  con- 
nection with  tlie  probable  Cambrian  exposures.  It  is  probable  that 
along  here  not  only  the  Eureka  quartzite,  but  the  whole  Silurian  sec- 
tion, is  exposed. 

Crossing  the  separate  low  ridges  which  constitute  the  connection 
between  the  southern  end  of  the  Egan  Range  and  the  Pahroc  Range, 
what  is  almost  certainly  the  Eureka  quartzite  was  found  about  25 
miles  northwest  of  Pioche.  Here  was  found  a  white  vitreous  quartz- 
ite, rather  coarse  grained  and  upward  of  100  feet  thick,  above  which 
lie  dark-graj',  comparatively  thin  fetid  crystalline  limestones,  with 
the  fossils  too  much  altered  to  be  recognizable.  This  is  perhaps  the 
Lone  Mountain  limestone.  These  Silurian  rocks  are  exposed  only 
along  the  eroded  axis  of  an  east-west  anticline,  and  to  the  north 
and  south  are  overlying  rocks  from  which  Devonian  fossils  were  col- 
lected. The  general  structure  of  the  beds  at  this  point  makes  it 
probable  that  a  little  farther  northeast  a  greater  thickness  of  Silurian 
rocks  is  exposed,  in  the  valley  midway  between  this  point  and  the 
Highland  Range. 

DEVONIAN. 

The  western  face  of  the  Egan  Range  about  8  or  10  miles  north  of 
Cherry  Creek  is  composed  of  stratified  rocks  dipping  very  gently 
northwest.  These  stratified  rocks  are  limestones  whose  appearance 
suggests  the  Nevada  formation  of  the  Devonian.  A  short  distance  north 
of  these,  also  on  the  west  face  of  the  range,  black,  shaly,  fetid  lime- 
stones carrying  Upper  Carboniferous  fossils  were  obtained,  wuile 
south  of  the  supijosed  Devonian  rocks,  in  the  neighborhood  of  Cherry 
Creek,  there  are  exposed  Silurian  f  ormatious,  as  already  mentioned.  It 
is  more  than  x^robable,  therefore,  that  the  intervening  rocks  are  really 
Devonian.     Mr.-  Emmons  has  made  the  same  suggestion.* 

In  the  canyon  which  cuts  through  the  range  at  Ely  limestones  carry- 
ing Lower  Carboniferous  fossils  were  found.  In  these  limestones  are 
siliceous  beds  which  may  perhaps  represent  the  Diamond  Peak 
quartzite  of  the   Eureka   section,   beneath   which  there  is  a  slight 

nU.  S.  C4eol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  488. 

Bull.  208—03 4 


50  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

exposure  of  shaly  limestone  which  may  represent  the  White  Pine 
formation.  No  fossils,  however,  were  procured  from  these  beds,  and 
their  identification  as  Devonian  is  only  provisional. 

At  the  northern  end  of  the  curving  spur  which  joins  the  main  range 
near  this  point  (PL  Y,  A),  where  it  passes  under  andesitic  flows  just 
south  of  Summit  stage  station  Cyathojjhyllum  sp.  was  found,  and  was 
referred  to  the  Devonian  by  Dr.  George  H.  Girty. 

This  Devonian  area,  however,  is  small,  since  at  a  distance  of  2  miles 
farther  south  similar  limestones  carrying  Carboniferous  fossils  were 
found. 

Devonian  rocks  make  uj)  nearly  the  whole  of  the  series  of  low  ridges 
which  constitute  the  extreme  southern  end  of  the  Egan  Range,  so  far 
as  these  rocks  were  examined  bj^  the  writer  in  crossing  diagonally  from 
northwest  to  southeast.  In  crossing  the  pass  which  cuts  through 
the  western  and  main  ridge  of  these  mountains,  about  10  miles  due 
southeast  from  Adams's  ranch,  comparatively  thin-bedded  fetid  lime- 
stones were  found  folded  into  a  syncline  striking  diagonally  to  the 
trend  of  the  pass,  and  carrying  the  following  Devonian  fossils,  as 
determined  by  Dr.  George  H.  Girty: 

Amphipora?  sp. 
Cladopora?  sp. 
Stromatoporoid  coral. 
Chonetes  macrostriatus. 
Spirifer  utahensis. 

The  corals  obtained  here  make  up  the  greater  bulk  of  the  rock, 
which  appears,  therefore,  to  have  been  a  Paleozoic  coral  reef.  Both 
the  fossils  and  the  nature  of  the  inclosing  rocks  are  identical  with 
the  fossils  and  rocks  found  in  the  Golden  Gate  Range,  directly  west 
of  here  and  about  15  miles  distant. 

Following  the  road  from  here  southeastward  to  Pioche,  Devonian 
fossils  were  again  obtained  about  12  miles  south  of  the  first  localitj^ 
as  follows: 

Amphipora?  sp. 
Stromatoporoid  corals. 
Spirifer  mala  (small  variety). 

Again  about  6  miles  farther  southeast  the  following  Devonian  fos- 
sils were  collected: 

Fucoid. 

Prodtictella  stibaculeata. 
Rliipidomella  sp. 
Spirifer  disjnncttis. 
Spirifer  iitaliensis. 
Spirifer  strigosus  ? 
Ambocoelia  umbonata. 
Camarotoecliia  sappho. 
Modiomorpha  obtusa  ? 
Grammysia  minor  ? 
Losonema?  sp. 


U.    S.    GEOLOGICAL  SURVEY 


JLLETIN     NO.    208        PL.    V 


A.      EAST    FACE   OF    LOW    MOUNTAIN    RANGE   WEST  OF    EGAN    RANGE  AT   ELY. 


JB.     TERTIARY  VOLCANIC   CONE,    PANCAKE   RANGE,    EAST  SIDE   OF    HOT   CREEK. 
Exposed  by  denudation  of  overlying  lavas  and  tuffs. 


SPURR.]  EGAlSr    RANGE.  51 

The  structure  of  the  surrounding  ridges  makes  it  probable  that  most 
of  them  are  Devonian. 

CARBONIFEROUS. 

In  the  extreme  northern  end  of  the  Egan  Range  Mr.  Emmons'*  col- 
lected probable  Carboniferous  fossils.  On  the  western  front,  about 
12  miles  north  of  Cherry  Creek,  the  following  fossils  were  collected  by 
the  writer  and  identified  by  Dr.  Girty : 

Orbiculoidea  missouriensis  ? 
Marginif era  splendens  ? 
Prodiictus  11.  sp. 
Spirorbis  sp. 
Euoniphalus  catilloldes. 

Between  Egan  Canyon  and  Ely  it  is  probable  that  the  Carboniferous 
rocks  cover  a  considerable  area.  Near  Ely,  Carboniferous  limestones 
are  abundantly  exposed.  About  2  miles  south  of  Summit  Springs, 
on  the  road  between  Ely  and  Hamilton,  massive  semicrj^stalline  lime- 
stones are  found  which  carry  a  probablj^  Upper  Carboniferous  fossil 
that  was  determined  by  Dr.  Girty  as  Zaplirentis  sp. 

About  6  miles  east  of  here,  on  the  east  side  of  the  narrow  valley 
separating  the  minor  ridge,  in  which  the  above  fossil  was  obtained, 
from  the  main  range,  were  collected  the  following  Upper  Carbonifer- 
ous fossils: 

Seminula  subtilita? 
Lithostrotion  ?  sp. 
Ftistilina  cylindrica. 

Two  miles  southeast  of  the  last-named  locality,  near  the  western 
entrance  of  the  canyon  which  cuts  through  the  range  at  Ely,  dark- 
gray  carbonaceous  fetid  limestones  were  found  which  carry  the  fol- 
lowing Lower  Carboniferous  fossils : 

Zaplirentis  sp. 
Ortliotlietes  ingequalis. 
Rhipidomella  miclielini. 
Productus  serdireticulatris  var. 
Prodiictus  n.  sp. 
Spirif  er  ceiitronatiis. 
Straparollus  liixus. 
Proetus  peroecidens. 

The  black  shaly  limestone  which  carries  the  Lower  Carboniferous 
fauna  at  the  last-named  locality  passes  into  a  belt  of  red,  yellow,  and 
orange  weathering  shales,  with  occasional  beds  of  gray,  shaly  lime- 
stone. The  thickness  of  these  shales  is  estimated  at  from  800  to 
1,000  feet.  Farther  east  in  the  canyon  beds  of  cherty  and  siliceous 
limestones  also  occur  in  this  same  series.  It  is  probable  that  the  low- 
est of  these  shaly  beds  are  Devonian,  but  to  the  south  of  Ely,  above 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II.,  p.  487 


52  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

the  shales,  the  more  massive  limestone  comes  in  above  again  and 
extends  for  5  or  6  miles  at  least,  striking  east  and  west  and  dipping 
gently  south. 

On  the  southeastern  slope  of  Hamels  Peak,  some  miles  south  of  Ely, 
the  fossils  named  below  were  collected  by  Mr.  F.  B.  Weeks,^  and  were 
determined  by  Dr.  Girty.  Regarding  this  collection,  Mr.  Girty  states 
"The  fauna  has  a  similar  fades  to  that  of  the  Marion  formation  of 
the  Kansas  section,  which  Prosser  regards  as  a  true  Permian  fauna, 
and  it  probably  can  be  safely  correlated  with  the  Marion." 

Producttis  sp. 
Nuculana  cf .  obesa. 
Pleurophortis  ?  sp. 
Schizodus  ?  sp. 
Straparollus  catilloides. 
Pletirotomaria  htimerosa  ? 
Bulimorpha  per  acuta. 
Murchisonia,  near  marcouiana. 
Naticopsis  ventricosa  ? 
Bellerophon  sp. 
Domatoceras  ?  sp. 
Ostracoda. 
Bakewellia  parva. 

IGNEOUS   ROCKS. 


On  the  west  side  of  the  Egan  Range,  just  north  of  Egan  Canyon,  a 
series  of  low  hills  are  composed  of  basalt.  One  of  these  hills  has  a 
conical  shape  practically  unmodified,  and,  from  the  circumstance  of 
this  slight  erosion,  the  age  of  the  lava  must  be  very  recent. 

Farther  south,  also  on  the  west  side  of  the  range,  is  a  considerable 
mass  of  volcanic  rock  which  has  filled  up  the  vallej^  between  the 
southern  end  of  the  Long  Valle}^  Range  and  the  Egan  Range  north 
of  Ely.  This  is,  in  general,  a  dacite-andesite  and  has  been  deeply 
eroded,  indicating  greater  age  for  it  than  for  the  basalt. 

At  the  southern  end  of  the  range,  in  the  sei3arate  low  ridges  which 
form  the  connection  of  this  range  with  the  Pahroc  Range,  there  are 
large  areas  of  quartz-latite  which  seem  to  be  continuous  with  similar 
lavas  occurring  in  the  northern  end  of  the  Golden  Gate  Range  and 
on  the  easterly  side  of  the  Grant  Range  in  the  same  latitude.  As  in 
the  other  cases  described,  it  is  plain  that  these  outflows  occurred 
subsequent  to  the  formation  of  the  deep  valleys  between  the  limestone 
ridges,  for  the  volcanic  rock  either  fills  up  such  valleys  or  has  been 
poured  into  them  without  quite  filling  them  up  and  now  forms  their 
floor.  Nevertheless,  this  volcanic  rock  is  also  deeply  eroded,  and 
therefore  its  age  is  not  recent.  It  may  be  considered  as  very  late 
Tertiary  or  early  Pleistocene. 

a  Personal  commuication  to  the  writer. 


SPURR.]  EGAK   RANGE  58 

DIKES. 

At  tlie  western  entrance  of  the  canyon  wliich  cuts  through  the  range 
at  Ely  a  dike  of  hornblende-tonalite-porphjay  was  noted.  Farther 
east  in  the  eanj^on  occur  a  number  of  other  siliceous  dikes.  These 
dikes  probably  connect  with  a  larger  body  farther  south,  which  seems 
to  form  the  crest  of  the  range  in  the  ^dcinit5^  of  Howells  Peak. 

Just  west  of  the  town  of  Cherry  Creek  occur  a  number  of  dikes 
which  are  apparently  connected  with  a  larger  igneous  body  a  little 
farther  north.  Specimens  of  these  dikes  show  them  to  be  chiefly 
quartz-monzonites. 

STRUCTURE. 


The  extreme  northern  end  of  the  range  is  said  by  Mr.  Emmons^  to 
present  an  anticlinal  fold  striking  northeasterly,  and  so  diverging 
from  the  general  trend  of  the  mountains.  Farther  south,  but  still 
north  of  Egan  Canyon,  the  general  structure  is  plainlj^  synclinal, 
and  has  the  same  northeasterly  trend.  This  syncline  must  succeed 
the  anticline  to  the  southeast.  In  the  vicinity  of  Egan  Canyon,  on  the 
eastern  side  of  the  range,  the  strata  on  the  eastern  limb  of  this  syn- 
cline dip  to  the  Avest  at  angles  of  from  30°  to  45°,  which  gradually 
grow  less  to  the  west  until,  at  a  point  about  8  or  10  miles  north  of 
Cherry  Creek,  and  on  the  west  side  of  the  range,  easterly  dipping 
strata  constituting  the  other  side  of  the  syncline  are  found. 

Between  the  Cambrian  rocks  on  the  eastern  side  of  Egan  Canyon 
and  the  same  formations  on  the  west  face  of  the  Schell  Creek  Range, 
only  a  few  miles  to  the  east,  there  is  probably  an  anticlinal  fold 
occupying  Steptoe  Valley. 

From  Egan  Canyon  south  the  Egan  Range  may  be  seen  to  consist 
of  stratified  rocks  as  far  as  Ely,  but  the  general  northeasterly  trend 
of  the  beds  at  Egan  Canyon  changes  to  a  northwesterly  one  in  the 
mountains  north  of  Hercules  Gate,  about  10  miles  north  of  Ely.  The 
general  structure  of  the  mountains  at  this  point  seems  lobe  synclinal, 
the  western  limb  of  the  fold  being  exposed  in  the  Devonian  limestone 
lying  just  south  of  Summit  stage  station  on  the  road  between  Ely  and 
Hamilton.     These  limestones  dip  to  the  east  at  an  angle  of  20°. 

From  Ely  south  for  a  number  of  miles  the  strata  are  not  conspicu- 
ously folded,  but  dip  gently  in  various  directions,  chiefly  to  the  south. 
The  whole  southern  end  of  the  range,  however,  from  a  point  about  10 
or  15  miles  south  of  Ely  as  far  as  the  point  where  the  main  range 
begins  to  split  up  into  several,  shows  beds  which  strike  uniformly 
northeast,  at  an  angle  with  the  general  north-south  trend  of  the 
mountains.  The  farther  south  one  goes  the  more  easterly  becomes 
the  strike  of  the  strata,  until,  in  the  series  of  low  ridges  at  the  south- 

a  U.  S.  Geol.  Expl. Fortieth  Par.,  Vol.  H,  p.  486. 


54  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH   PARALLEL.     [BULt..208. 

ern  end  of  the  range,  it  swings  aronnd  to  east-west  and  then  to  south- 
east, and  so  runs  into  the  Pahroc  Range,  where  it  becomes  due  north 
and  south. 

In  this  southern  i3art  of  the  range  many  parallel  open  folds  are 
exposed.  On  the  west  face,  about  30  miles  north  of  Adams's  ranch,  in 
Sierra  Valley,  the  axis  of  a  broad  syncline  may  be  traced,  with  the 
rocks  on  both  sides  dipping  from  10°  to  30°.  This  is  followed  to  the 
south  hy  a  slight  anticline  and  this  by  a  broad  syncline,  whose  axis 
cuts  the  mountains  about  10  miles  southeast  of  Adams's  ranch,  at 
the  pass  through  which  runs  the  road  to  Pioche.  South  of  here  the 
succeeding  anticlines  and  synclines  are  frequent  and  regular.  Since 
their  strike  is  transverse  in  general  to  the  trend  of  the  ridges  and 
since  different  ridges  are  composed  of  the  same  i-ocks,  the  folds  may 
be  traced  from  one  to  the  other  for  long  distances.  Thus,  south  of 
the  synclinal  fold  above  described  a  broad  anticline  was  observed, 
which  comprises  the  rocks  for  a  distance  of  about  10  miles  to  the 
south  and  which  has  in  general  an  east-west  trend.  South  of  this 
a  comparatively^  narrow  syncline  exists,  and  south  of  this  again  an 
anticlinal  fold,  which  after  swinging  from  an  east-west  to  a  south- 
easterly direction,  appears  to  change  still  more.  Mil  it  enters  the 
Pahroc  Range  with  a  north-south  trend  and  constitutes  the  chief  fold 
of  these  mountains. 

In  general,  therefore,  the  Egan  Range  consists  of  open  and  sym- 
metrical anticlines  and  synclines,  with  the  rocks  rarely  dipping  more 
than  30°.  In  general  these  folds  trend  more  easterly  than  the  general 
trend  of  the  mountains,  and  thus  a  number  of  succeeding  folds  are 
exposed. 

FAULTING. 

In  the  southern  part  of  the  range  several  deep  transverse  valleys 
suggest  fault  lines,  but  the  examination  was  too  hasty  to  be  sure  of 
their  existence. 

ORES. 

At  Mineral  City,  just  west  of  Ely,  lead,  silver,  and  gold,  with  son>e 
copper,  are  obtained.  At  this  locality''  a  number  of  siliceous  dikes  cut 
up  through  the  limestone,  and  seem  to  be  connected  with  the  miner- 
alization. In  the  neighborhood  of  Elj^  there  are  considerable  ore 
deposits.  At  Cherry  Creek  also  the  dikes  have  perhaps  brought  about 
the  deposition  of  the  minerals.  Some  of  the  ore  deposits  here  run 
comparatively  high  in  gold  and  silver. 

LONG  VALLEY  RANGE. 

Long  Valley  Range  consists  of  low  limestone  mountains.  Its  south- 
ern end,  just  east  of  Hamilton,  is  united  with  the  White  Pine  Range 
bj^  a  series  of  connecting  north-south  parallel  ridges.  On  the  north 
it  extends  up  into  the  area  of  the  Fortieth  Parallel  surveys,  where  it 
is  represented  by  a  series  of  detached  low  limestone  mountains  and 
finally  dies  out  in  the  valley. 


SPURR.]  LONG    VALLEY    EANGE.  55 

TOPOGRAPHY. 

The  Long  Valley  Range  consists  in  general  of  a  single  main  ridge, 
on  both  sides  of  which  the  ascent  from  the  base  is  comparatively 
gentle.  The  interrupted  form  of  the  northern  end  of  the  range, 
resulting  in  detached  clumps  of  hills,  has  probably  been  brought 
about  b}^  erosion,  which  has  cut  deep  into  the  ridge  and  formed  val- 
lej's  which  were  afterwards  filled  up  with  detrital  material,  on  a  level 
with  that  of  the  main  valleys  between  the  ranges.  On  the  eastern 
side  of  the  south  end  of  the  range  a  great  flood  of  andesitic  lava  has 
filled  a  former  valley  to  a  height  equal  in  general  to  that  of  the  pre- 
existing ridges. 

This  andesite  itself  has  been  considerably  eroded.  The  valleys 
which  have  been  cut  in  it,  being  younger  than  the  main  vallej^  into 
which  the  lava  was  poured,  are  instructive  as  to  the  manner  of  the 
formation  of  desert  valleys  in  general  and  their  filling  up  with  detrital 
accumulations.  Each  of  these  narrow  valleys  in  the  lava,  often  only 
a  few  hundred  feet  wide,  presents  in  a  small  way  all  the  character- 
is|-ics  of  the  larger  valleys  which  separate  the  ranges.  In  the  middle 
is  a  flat  sage-brush  plain,  and  on  the  sides  long  gentle  slo]3es  of  wash 
proceed  from  the  gullies  which  cut  up  the  adjoining  ridges.  In  these 
deposits  of  the  smaller  valleys,  as  in  those  of  the  larger  valley,  there 
is  no  trace  of  deposition  in  the  presence  of  water,  but  the  vallej^s 
have  filled  up  evenly  and  smoothly  with  dry  material,  distributed 
perhaps  in  part  by  rivulets  and  by  wind  storms. 

SEDIMENTARY    ROCKS. 
CARBONIFEROUS. 

At  the  south  end  of  the  range  a  section  was  followed  along  a  portion 
of  the  road  between  Hamilton  and  Ely.  The  rock  hei^e  is  a  limestone, 
often  cherty  or  aphanitic.  Under  the  microscope  the  chert  shows 
cross  sections  of  organic  forms.  The  western  edge  of  the  section 
yielded  the  following  Upper  Carboniferous  fossils,  which  were  deter- 
mined by  Dr.  Girty: 

Marginifera  imiricata? 
Productus  prattenianus. 
Prodtictus  inflatus? 

Farther  east  the  following  Upper  Carboniferous  fossils  were  col- 
lected from  the  same  limestone  at  a  horizon  several  hundred  feet 
higher  than  the  above : 

Fenestella?  sp, 
Campophyllum  torquium? 
Productus  prattenianus. 
Fusulina  cylindrica. 
Rhombopora  lepidodendroides. 
Fistulipora?  sp. 
Productus  semireticulatus. 


56  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH   PARALLEL,     [bull.208. 

Only  about  1,000  feet  of  strata  are  exposed  in  this  section,  owino-  to 
the  low  dip  of  the  rocks. 

On  the  north  end  of  the  range  the  separated  groups  of  low  moun- 
tains above  mentioned  appear  to  be  almost  entirelj'  composed  of  Car- 
boniferous limestone.  They  are  so  shown  on  the  maps  of  the 
Fortieth  Parallel  Survey.  Tlie  writer  collected  two  lots  of  Upper 
Carboniferous  fossils  at  the  northern  end  of  the  limestone  mountain 
which  lies  just  east  of  Franklin  Lake  and  the  northern  end  of  Ruby 
Lake.  This  is  ]3ractically  the  northern  terminus  of  the  Long  Valley 
Range,  although  in  the  Fortieth  Parallel  maps  it  is  given  under  the 
head  of  the  Ruby  Group  of  Mountains. 

According  to  Dr.  Girtj^'s  determination,  the  first  locality  yielded 
Marginifera  splendens  ? 

The  second  locality  afforded  the  following: 

Chonetes  flemingi. 
Productus  subliori-idus. 
ProdiTcttis  mi-iltistriatus. 
Spirifer  cameratus? 
Spiriferina  pulchra. 
Semintila  mira. 

South  of  the  lava  area  which  fills  the  vallej^  between  the  Long  Val- 
ley Range  and  the  Egan  Range,  on  the  road  from  Hamilton  to  Ely, 
there  is  a  narrow  spur  of  mountains  running  from  the  neighborliood 
of  Summit  stage  station  to  the  Egan  Range,  south  of  Ely.  This  may 
be  considered  as  an  outlying  spur  of  the  Egan  Range,  but  yet  may 
extend  beneath  the  lava  and  so  form  a  connection  with  the  Long 
Valley  Range.  From  the  rocks  of  this  spur  at  a  point  just  south  of 
Summit  station  a  Devonian  coral  was  obtained.  Farther  south  in  the 
same  ridge  are  Carboniferous  fossils,  as  described  under  the  head  of 
the  Egan  Range  (see  p.  51). 

IGNEOUS   ROCKS. 

LAVAS. 

The  great  mass  of  lava  .Avhicli  flanks  the  eastern  side  of  th^  Long 
Valley  Range  proper  at  its  lower  end  has  alread}^  been  mentioned. 
The  extent  of  this  patch  of  lava  to  the  north  is  uncertain,  but  prob- 
ably is  not  more  than  10  or  15  miles.  To  the  south  it  passes  under 
the  Pleistocene  accumulations  of  Sierra  Valley,  while  to  the  east 
and  to  the  west  it  abuts  against  the  limestones  of  the  Egan  and  the 
Long  Valley  ranges.  As  noted  above,  this  lava  has  been  considerably 
eroded.  Thin  sections  of  the  rock  show  it  to  be  in  general  a  dacite- 
andesite,  the  prevalent  type  being  a  dacite  containing  augite,  biotite, 
and  hornblende. 

STRUCTURE. 

FOLDING. 

A  section  taken  at  the  southern  end  of  the  range  shows  a  mono- 
clinal  structure  for  the  main  ridge.     In  reality,  however,  this  is  the 


SPtTRR.]  GOLDEN    GATE    EANGE.  57 

east  side  of  an  anticline  whose  axis  lies  in  a  narrow  valley  to  the  west 
of  the  main  ridge  and  wiiose  easterly  limb  is  exposed  in  the  next  ridge 
to  the  west  (see  fig.  1,  p.  66). 

The  spnr  of  Devonian-Carboniferons  rocks  described  on  page  56  is 
separated  from  the  main  ridge  by  Pleistocene  deposits  and  by  lava, 
and  the  structural  connection  is  not  shown,  but  in  itself  it  exhibits  a 
series  of  somewhat  closely  compressed  regular  open  folds  with  north- 
south  strike,  changing  to  a  northwest-southeast  strike  as  the  si3ur 
approaches  the  Egan  Range.  In  this  minor  ridge  there  is  exjjosed, 
beginning  with  the  most  westerly  fold,  an  anticline,  a  syncline,  a  sec- 
ond anticline,  and  a  second  s^yncline. 

For  the  main  ridge  of  the  Long  Valley  Range  the  general  strike  is 
seen  to  be  parallel  to  the  general  trend  of  the  mountains;  that  is,  a 
little  east  of  north.  At  the  north  end  of  the  range,  at  the  fossil  local- 
ities, a  slight  syncline  with  a  general  north-south  strike  was  observed 
in  the  Carboniferous  limestone. 

GOLDEN  GATE  RANGE. 

The  Golden  Gate  Range  scarcely  deserves  a  separate  name,  on 
account  of  its  comparative  insignificance.  This  name  is  applied  to 
a  connected  series  of  low  mountains  which  lies  to  the  east  of  the 
Grant  Range,  and  properly  has  a  north-south  extent  of  not  more  than 
25  miles,  with  an  average  width  of  3  or  4  miles.  On  the  south  the 
Golden  Gate  Range  is  connected  by  low  hills  with  the  northern  exten- 
sion of  the  Hiko  Range,  while  on  the  north  the  range  dies  awa}^  into 
the  Sierra  Valley.  Twentj^-five  miles  north  of  the  north  end  of  the 
range  there  is  a  chain  of  low  hills  running  north  and  south  and  lying 
midway  between  the  White  Pine  Range  and  the  Egan  Range.  These 
hills  might  perhaps  be  considered  as  the  northern  continuation  of  the 
Golden  Gate  Range,  the  intervening  portion  being  covered  up  by  the 
Pleistocene  accumulations  of  Sierra  Valley. 

TOPOGRAPHY. 

The  mountains  which  make  up  the  Golden  Gate  Range  are  entirely 
detached  from  one  another,  and  are  separated  by  narrow  stretches 
of  Pleistocene  valley  deposits,  on  a  general  level  with  the  vallej^s  on 
both  sides  of  the  range.  The  separate  groups  are  sometimes  composed 
of  stratified  rocks  and  sometimes  of  lava.  The  hills  of  stratified  rock 
are  scarped  along  the  axes  of  anticlinal  folds.  They  are  therefore 
scarped  on  both  sides  Avhen  they  are  synclinal,  while  when  they  are 
anticlinal  the}'  have  in  general  smooth  sides  with  a  sharp  downcutting 
in  the  center.  The  groups  which  are  composed  of  volcanic  rocks  have 
naturally  a  milder  and  more  uniform  topography. 

SEDIMENTARY   ROCKS. 
SILURIAN. 

An  isolated  butte  at  the  northern  end  of  the  Golden  Gate  Range, 
not  verj"  far  from  Adams's  ranch  on  White  River,  exposes  a  verj^  inter- 


58  GEOLOGY    OF   l^EVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

esting-  section  of  Silurian  rocks.  The  beds  here  striliie  N.  35°  W.  and 
dip  30°  NE.  At  the  base  of  the  section  is  300  feet  of  thin-bedded, 
somewhat  fetid  limestone  and  limy  shale.  Above  comes  250  feet  of 
white  vitreous  quartzite,  which  is  undoubtedly  the  Eureka  formation. 
Above  this  comes  about  800  feet  of  comparatively  massive  brownish 
limestone  (the  Lone  Mountain  formation).  At  a  point  about  150 
feet  below  the  bottom  of  the  Eureka  quartzite,  in  the  Pogonip  lime- 
stone, Ordovician  fossils  were  found.  They  have  been  determined  by 
Dr.  Girtj^  as  follows: 

Ortliis  perveta. 
Maclurea  sp. 
Murchisonia  sp. 
Pleurotomaria  sp. 
Leperditia  bivia. 
lUaeniTS  sp. 
Trilobites  undet. 

DEVONIAN. 

Southwest  from  this  butte  and  about  10  miles  distant  is  a  consider- 
able clump  of  hills,  which  forms  one  of  the  chief  features  of  the  range. 
A  section  of  about  2,000  feet  of  limestone  is  here  exposed.  The  lower 
1,000  feet  is  of  limestone,  which  in  places  has  the  peculiarity  of 
weathering  brown  and  craggy,  like  quartzite.  The  upper  1,000  feet  is 
composed  of  shale  and  thin-bedded  limestone.  In  the  lower  limestone, 
where  it  was  examined,  the  rocks  are  chiefly  composed  of  corals  and 
constitute,  therefore,  part  of  a  Devonian  coral  reef.  The  same  reef, 
with  the  same  corals,  was  found  in  the  ridges  which  form  the  southern 
continuation  of  the  Egan  Range,  12  or  15  miles  east  of  here.  The 
following  Devonian  fossils  were  identified  by  Dr.  Girty: 

Amphipora?  sp. 
Stromatoporoid  coral. 
Indeterminable  gasteropod. 

PLEISTOCENE. 

As  before  noted,  the  hills  of  the  Golden  Gate  Range  are  surrounded 
and  often  separated  by  accumulations  of  Pleistocene  material.  This 
material  is  generally  angular  and  bears  the  marks  of  having  been 
brought  to  its  present  position  by  the  influence  of  rains,  wind,  and 
gravity,  not  by  stream  or  lake  action.  Probably  this  Pleistocene 
forms  a  veneer  over  underlying  Tertiary  deposits,  as  is  the  case  in 
the  next  valley  to  the  west — Railroad  Valley. 

In  the  neighborhood  of  the  Silurian  butte  above  mentioned  is  an 
extensive  deposit  of  calcareous  hot  spring  tufa,  covering  apparently 
an  area  of  several  square  miles  and  eroded  into  hills  and  bluffs  in 
places  40  feet  high.     Within  this  area  active  hot  springs  are  plentiful. 

IGNEOUS  ROCKS. 

Several  of  the  eminences  of  the  Golden  Gate  Range  are  composed 
of  volcanic  rocks,  which  also  surround  some  of  the  hills  of  stratified 


SPURR.]  aOLDEN    GATE    AND    HUMBOLDT   RANGES.  59 

rocks  and  apparently  extend  to  the  east  to  the  southern  end  of  the 
Egau  Range,  as  represented  on  the  map.  A  specimen  of  the  lava 
from  the  north  end  of  the  Golden  Gate  Range  proved  to  be  quartz-latite. 

STRUCTURE. 

FOLDING. 

In  the  stratified  rocks  of  the  Golden  Gate  Range  the  strike  runs 
diagonally  or  transversely  to  the  general  trend  of  the  mountains.  It 
has  been  noted  how  in  the  southern  part  of  the  Schell  Creek  and  Egan 
ranges  the  folds  have  northeast  and  southwest  axes,  which  are  diag- 
onal to  the  general  trend  of  these  ranges.  In  the  Pahroc  Range  the 
trend  of  the  axes  of  folding  seems  to  be  north  and  south,  parallel  with 
the  mountains.  Between  the  Pahroc  and  the  Egan  ranges  there  is  an 
area  containing  a  number  of  minor  cross  folds,  which  have  a  curving 
axis  and  which  extend  to  and  connect  with  the  folds  of  the  Golden 
Gate  Range.  Several  of  these  minor  folds  seem  to  die  out  just  west 
of  the  Golden  Gate  Range. 

The  anticlinal  fold  which  marks  the  rocks  of  the  northernmost  and 
chief  group  of  hills  of  the  range  in  which  the  Devonian  corals  were 
found  may  be  a  continuation  of  a  possible  broader  anticlinal  axis 
running  between  the  Worthington  Mountains  and  the  northern  end 
of  the  Hiko  Range.  The  folds  of  the  Golden  Gate  Range  lying  south 
of  this  anticline,  comprising  two  more  anticlines  with  intervening 
synclines,  do  not  have  any  visible  relation  to  the  folds  to  the  west  or 
south.  However,  they  raay  be  traced  continuously  to  the  east  across 
the  several  ridges  which  mark  the  southern  end  of  the  Egan  Range. 
The  southernmost  folds  curve  around  southeasterly  toward  the  Pah- 
roc Range,  while  the  northerly  ones,  diverging  from  the  others,  main- 
tain a  northeasterly  direction. 

FAULTING. 

In  the  neighborhood  of  the  Silurian  butte  above  mentioned  the 
abundance  of  hot  springs  suggests  the  presence  of  faults,  but  this 
could  not  be  established. 

HUMBOLDT  RANGE. 

The  Humboldt  Range  is  the  most  important  mountain  ridge  in  the 
Great  Basin  between  the  Wasatch  and  the  Sierra  Nevada.  Its  south- 
ern end  only  was  visited  by  the  writer,  and  as  this  has  already  been 
mapped  and  explored  by  the  geologists  of  the  Fortieth  Parallel  Sur- 
vey, it  is  unnecessary  here  to  go  into  details.  But  inasmuch  as  the 
writer  collected  fossils  in  localities  from  which  none  had  been  reported, 
it  is  thought  advisable  to  insert  this  short  description. 

TOPOGRAPHY. 

North  of  Fremont  Pass  the  Humboldt  Range  is  exceedingly  rugged 
and  precipitous.     South  of   the  pass  the  mountains  become  lower. 


60  GEOLOGY    OF   KEYADA  SOtJTH    OF   40TH    PARALLEL,    [bull. 208. 

At  Hastings  Pass  tliey  are  of  only  moderate  height,  and  the  ascent  from 
the  base  on  both  sides  to  the  summit  is  not  precipitous.  South  of 
Hastings  Pass  the  mountains  are  still  lower,  and  pass  into  straggling 
groups  which  connect  with  the  northern  extension  of  the  White  Pine 
Range. 

SEDIMENTARY   ROCKS. 

North  of  Fremont  Pass  the  Humboldt  Range  consists  mainlj^  of 
Archean  rocks,  as  has  been  described  by  King''  and  Hague. ^  These 
rocks  consist  of  a  series  of  gneisses  and  schists  overlying  the  basal 
granite  and  having  a  thickness  of  8,000  or  10,000  feet.  Of  this  series 
the  lower  5,000  feet  is  in  general  a  mica-gneiss,  while  the  upper  5,000 
feet  is  a  hornblendic  and  dioritic  schist,  containing  veins  of  quartzite. 
At  the  top  are  beds  of  limestone  and  quartzite.  Above  this  gneiss 
and  schist  series  comes  a  series  of  quartzites  about  2,000  feet  thick. 
The  quartzites  are  white  or  yellow-brown  in  color  and  contain  sec- 
ondary garnet,  hornblende,  actinolite,  muscovite,  biotite,  and  iron 
oxide.  On  them  rest  unconformably  the  Paleozoic  strata,  with  the 
Devonian  generally  at  the  base  and  the  Carboniferous  above. 

King  notes  the  resemblance  of  the  quartzite  series  (which  lies 
unconformably  beneath  the  Paleozoic  beds)  to  similar  rocks  in  the 
Wasatch  Mountains.  It  is  possible  also  that  the  thick  white  and 
brown  Cambrian  quartzites  exposed  in  the  Snake  Range,  especiallj'^ 
in  the  vicinity  of  Jeff  Davis  or  Wheeler  Peak,  may  be  equivalents  of 
the  Humboldt  quartzite. 

South  of  Fremont  Pass  the  eastern  face  of  the  range  is  composed  of 
easterly  or  southeasterly  dipping  limestones.  At  a  i3oint  not  more 
than  4  miles  south  of  the  pass  the.  following  Coal  Measures  fossils  were 
collected  by  the  writer  from  a  butte  at  the  base  of  the  mountains. 
They  were  determined  by  Dr.  Girty  as  follows : 

Fisttilipora  sp. 
Campophyllum  torquiiim? 
Lophophyllnm  proliferain. 
Rhipidomella  pecosi. 
ProcUictiTS  sp. 
Spirifer  camerattis. 

These  same  limestones  continue  all  along  the  east  face  of  the  range 
as  far  as  Hastings  Pass.  On  the  summit  of  the  pass  is  found  a  con- 
siderable thickness  of  sandstones  mixed  Avith  fine  conglomerates. 
These  the  Fortieth  Parallel  geologists  regarded  as  Devonian  of  the 
Ogden  formation,  which  would  correspond  to  the  Diamond  Peak 
quartzite  of  the  Eureka  section.  A  short  distance  west  of  the  summit 
the  Paleozoic  rocks  are  overlain  unconformably  by  thick  deposits 
belonging  to  the  Humboldt  Pliocene  of  the  Fortieth  Parallel  Survey. 
At  the  upper  edge  of  the  Pliocene  deposits  the  material  consists  of 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.  62.  6 Idem,  Vol.  11,  p.  528. 


SPURR.]  HUMBOLDT    AND    WHITE    PINE    EANGES.  61 

large  angular  fragments  of  limestone.  From  some  of  the  largest  of 
these  fragments  fossils  were  obtained  which  were  determined  by 
Professor  Ulricli  as  Ordovieian. 

Leperditia  bivia  White. 
Leperditia  sp.  (nevadensis?). 
RhjTichonella? 

Stropliomena  minor  Walcott. 
Strophomeiia?  nemea  H.  &  W.? 
Dalmauella  perveta?  Walcott. 
Bathynrtis. 

If  Silurian  rocks  exist  in  place  at  this  point  one  may  well  snppose 
that  they  are  exposed  by  means  of  a  fanlt,  for  otherwise  the  thick- 
ness of  strata  in  the  mountains  seems  hardly  sufficient  to  account  for 
their  appearance. 

IGNEOUS   EOCKS. 

North  of  Fremont  Pass  the  basal  rock  appears  to  be  mica-granite,  as 
described  by  King.<*  South  of  Hastings  Pass  a  considerable  area  is 
also  represented  as  granite  in  the  Fortieth  Parallel  maps. 

STRUCTURE. 
FOLDING. 

The  general  structure  of  the  Humboldt  Range  is  a  broad  anticline, 
as  has  been  mentioned  by  King^  and  by  Hague,'^  and  as  can  be  seen 
by  an  inspection  of  the  maps  of  the  Fortieth  Parallel. 

FAULTING. 

It  appeared  to  the  Avriter  that  Fremont  Pass  is  the  line  of  an  east- 
west  fault,  and  that  this  explains  the  abutting  of  the  Paleozoic  rocks 
on  the  south  against  the  granite  and  Archean  on  the  north.  More- 
over, the  above-mentioned  Paleozoic  rocks  are  sharpl}'  turned  up 
along  this  supposed  fault  line,  so  that  they  dip  steeply,  and  their 
strike  swings  round  from  the  normal  north-south  direction  to  a 
northeasterly  one,  so  as  to  be  nearly  parallel  with  the  supposed  fault. 

The  possible  existence  of  a  fault  along  the  west  side  of  Hastings 
Pass  exposing  the  Silurian  rocks  has  been  mentioned  above. 

WHITE  PINE  RANGE. 

The  White  Pine  Range,  as  here  described,  is  the  southern  continu- 
ation of  the  Humboldt  Range,  and  its  northern  end  begins  about  10 
miles  south  of  Hastings  Pass,  in  that  range.  From  this  point  it 
extends  unbroken  southward  for  100  miles,  with  a  general  due  north- 
south  trend.  At  its  southern  end  it  is  continuous  with  the  short 
Grant  Range,  which  topographically  and  geologically  is  a  part  of  it, 
but  which  is  differently  named  and  will  be  described  separately. 

aJJ.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.64.  ''Ibid., p.  193.  <.^ Idem,  Vol.  II,  p.528. 


62  GEOLOGY    OF    NEVADA   SOUTH    OF   40TH   PARALLE'^u.     [bull. 208. 

TOPOGRAPHY. 

The  northern  jiart  of  the  White  Pine  Range,  from  the  southern  end 
of  the  Humboldt  Range  to  the  White  Pine  mining  district,  consists  of 
a  main  ridge,  which  is  narrow  and  not  very  high,  with  a  number  of 
minor  ridges  on  each  side,  separated  from  the  main  ridge  by  narrow 
valleys  in  which  the  underlying  rock  is  only  partly  obscured  bj^ 
Pleistocene  detritus.  In  the  vicinity  of  the  White  Pine  mining  dis- 
trict the  mountains  grow  higher  and  the  small  north-south  ridges 
change  into  a  complicated  group  of  irregular  mountains.  At  the 
same  time  the  main  ridge  broadens  out  to  four  or  five  times  its 
former  width. 

In  the  White  Pine  mining  district  three  mam  north-south  ridges 
may  be  distinguished — that  of  Pogonip  Mountain  on  the  west,  the 
minor  one  of  Treasure  Hill  in  the  middle,  and  that  of  Mokeamoke 
Ridge  on  the  east.  Still  farther  east  a  succession  of  regular  north- 
south  ridges,  similar  to  those  just  described  for  the  northern  part  of 
the  range,  form  a  continuation  of  the  southern  end  of  the  Long  Valley 
Range. 

Within  the  White  Pine  mining  district  the  mountains  reach  a  height 
of  10,000  feet  above  the  sea,  while  to  the  north  and  to  the  south  they 
are  considerably  lower.  To  the  south  of  the  district  also  the  moun- 
tains assume  something  of  the  same  simple  character  as  they  do  to 
the  north,  being  made  up  of  regular  north-south  ridges,  and  for 
the  most  part  consisting  of  a  single  main  ridge.  While  in  the  mining 
district  the  mountains  and  valleys  are  irregular,  the  topography  of 
the  range  to  the  north  and  to  the  south  is  quite  conventional,  showing 
a  nniform  succession  of  serrated  peaks  of  nearly  uniform  height,  with 
their  sides  furrow^ed  at  comparatively  regular  intervals  by  the 
drainage. 

Within  the  mining  district  the  irregularity  is  due,  as  will  be  pres- 
ently seen,  to  the  local  complexity  of  the  geologic  structure.  Pogonip 
Mountain,  which,  near  Hamilton,  juts  boldly  out  from  the  main  ridge 
and  is  the  highest  peak  in  the  whole  neighborhood,  has  a  bold  scarp 
to  the  north  and  to  the  Avest.  Throughout  the  district  there  are  a 
number  of  other  precipitous  cliffs.  But  in  the  rest  of  the  range  the 
mountains  show  the  same  steep,  but  yet  not  abrupt,  faces  that  are 
characteristic  of  the  other  ranges  of  the  region.  It  was  noticed,  how- 
ever, that  south  of  Hamilton  the  west  face  of  the  mountains  was  rather 
steeper  than  the  eastern  one. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

Pogonip  Mountain  is  composed  of  Paleozoic  strata  which  dip  in 
general  toward  the  east,  forming  the  western  limb  of  the  syncline 
whose  eastern  limb  is  exposed  on  the  west  side  of  Treasure  Hill  Ridge. 


SPUKR.]  WHTTE    PINP:    RANGE.  68 

On  the  western  side  of  Pogonip  Mountain  Mr.  Walcott  ^  has  deter- 
mined from  fossils  the  existence  of  the  Cambrian  Hamburg  limestone 
of  the  Eureka  section.  About  800  feet  of  the  Cambrian  is  exposed  at 
this  point. 

SILURIAN. 

Silurian  rocks  were  described  from  Pogonip  Mountain  by  Mr. 
Hague  ^  during  the  Fortieth  Parallel  Survey.  Later  on  the  Silurian 
beds  were  also  visited  and  reported  upon  by  Mr.  Walcott.''  Mr.  Wal- 
cott found  in  Pogonip  Mountain  the  following  formations,  divided 
according  to  the  Eureka  section : 

Section  at  Pogonip  Mountain. 

Feet. 

Lone  Moiintahi  limestone 1, 450 

Eiireka  qnartzite 350 

Pogonip  limestone 5, 200 

The  writer  obtained  from  Mr.  Grandelmeyer,  of  Hamilton,  a  fossil 
said  to  come  from  a  locality  about  6  miles  south  of  that  place.  It 
was  identified  by  Dr.  Girty  as  Receptaculites  sp.  and  assigned  to  the 
Ordovician. 

DEVONIAN. 

While  Pogonip  Mountain  is  composed  almost  entirely  of  Silurian 
strata,  the  ridge  next  east  is  made  up  almost  entirely  of  Devonian. 
Mr.  Hague  has  described  the  strata  and  their  contained  fossils  at  this 
point.  The  formation,  divided  according  to  the  Eureka  section,  com- 
prises the  Nevada  limestones  and  the  White  Pine  shales.  Besides 
this  Devonian  ridge,  the  writer  has  also  recognized  the  White  Pine 
Devonian  on  the  east  side  of  Mokeamoke  Ridge,  where  it  is 
repeatedly  brought  to  the  surface  beneath  the  Carboniferous  rocks 
by  the  erosion  of  anticlinal  folds.  He  has  moreover  traced  it  north 
of  the  White  Pine  mining  district  for  some  distance  along  the  west 
side  of  Mokeamoke  Ridge,  where  it  is  largely  hidden  by  Pleistocene 
detritus. 

CARBONIFEROUS. 

The  third  and  most  easterly  of  the  three  ridges  at  White  Pine, 
Mokeamoke  Ridge,  is  made  up  chiefly  of  Carboniferous  rocks  which 
carry  abundant  fossils.  A  list  of  Carboniferous  fossils  obtained  from 
Mokeamoke  Ridge  in  the  mining  district  is  given  by  Mr.  Hague. ^^ 
The  writer  has  traced  the  continuation  of  the  Carboniferous  belt  of 
Mokeamoke  Ridge  15  or  20  miles  north  of  the  mining  district.     At  a 

a  Mon.  U.  S.  Geol.  Survev  Vol.  XX,  p.  191. 
&U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  542. 
cQp.  cit.,  p.  191. 
dOp.  cit.,  p.  547. 


64  GEOLOGY    OF    NEVADA  SOUTH    OB^    40TH    PARALLEL,     [boll. 208. 

point  6  miles  north  of  Hamilton  Upper  Carboniferous  fossils  were 
collected.     The  following  were  determined  by  Dr.  Girty: 

Producttis  semh'eticulatus? 
Spirifer  boonensis. 
Seminula  siibtilita? 
Euomphalus  sp. 

In  the  same  rocks,  close  by  the  above  locality,  but  at  a  horizon 
about  200  feet  higher  up,  were  found  the  following: 

ProdiTctus  prattenianiis. 
ProdiictiTS  sp. 
Spirifer  boonensis. 
Seniintila  subtilita. 

The  minor  parallel  ridges  which  mark  the  northern  end  of  the  range 
have  all  the  aspect  and  structure  of  the  Carboniferous  limestones. 
The  writer  has  also  found  Upper  Carboniferous  limestones  lying 
directly  north  of  Pogonip  Mountain,  being  separated  from  the  Silu- 
rian rocks  at  this  point  by  a  heavy  east-west  fault  which  deter- 
mines the  northern  end  of  this  mountain.  Here  the  following  fossils 
were  collected: 

Lithostrotion?  sp. 
ProdiTctiis  sp. 
Spirifer  boonensis. 
Spiriferina  gonionotus. 
Seminula  mira? 
Bulimorpha  chrysalis? 

On  the  eastern  side  of  Moteamoke  Ridge  the  writer  has  traced  the 
Carboniferous  rocks  continuously  across  the  intervening  ranges  to  the 
southern  end  of  the  Long  Valley  Range. 

At  the  head  of  AUepaw  (Aj)plegarth?)  Canyon,  which  is  on  the  east 
side  of  the  range,  just  east  of  Hamilton,  Glyphioceras  sp.,  an  Upper 
Carboniferous  form,  was  found. 

Half  a  mile  farther  east,  down  the  canyon,  were  found  the  follow- 
ing .Upper  Carboniferous  fossils:  Marginifera  muricatas,  Productus 
semireticulatus,  Productus  prattenianus. 

Still  half  a  mile  farther,  at  the  old  pumping  station  for  the  town  of 
Hamilton,  were  found:  Orhiculoidea  sp.,  Productus  seniireticidatus, 
Productus  prattenianus,  Marginifera  muricata? 

Along  this  section  the  Carboniferous  rocks  alternate  with  narrow 
belts  of  the  underlying  Devonian,  which  is  exposed  by  the  erosion  of 
the  anticlinal  folds. 

The  Carboniferous  section  here  has  always  at  the  base  the  Diamond 
Peak  quartzite  of  the  Eureka  section.  This  quartzite,  or  rather  sand- 
stone (for  it  is  not  actually  a  quartzite),  outcrops  all  along  the  westerli 
base  of  Mokeamoke  Ridge,  so  far  as  this  has  been  followed,  and  has 
a  thickness  of  several  hundred  feet — much  smaller  than  at  Eureka. 
Above  the  sandstone  come  heavy,  blue  limestones  containing  Coal. 


sPL'iit;]  WHITE    PINE    RANGE.  65 

Measures  fossils.  In  the  Carboniferous  hillocks  at  tlie  northei'u  base 
of  Pogonip  Mountain  conglomerates  were  found  containing  joebbles 
of  red  and  purple  chert,  closely  resembling  similar  beds  just  west  of 
here,  on  the  east  side  of  the  Pancake  Mountains. 

RHYOLITE   ASH. 

North  of  the  White  Pine  mining  district  and  on  the  western  side  of 
Mokeamoke  Ridge,  the  broad  area  of  low  hills  is  partly  covered  by  a 
deposit  of  stratified  rhyoliticash.  NearSixmile  House,  6  miles  north 
of  Eureka,  a  dike  of  rhyolite  is  found  which  cuts  this  deposit  and 
shows  that  the  ash  is  the  earlier  of  the  two.  It  is  very  likely  that 
this  rhyolite  ash  is  of  the  same  age  as  that  ex]30sed  at  Twin  Springs 
in  the  Pancake  Range. 

IGNEOUS    ROCKS. 


The  existence  of  a  rhyolite  dike  in  the  vicinity  of  Sixmile  House 
has  just  been  referred  to.  In  this  neighborhood  and  farther  north 
one  finds,  together  with  the  rhyolite  ash  already  described,  numerous 
small  buttes  of  lava  which  have  been  eroded  into  separate  patches, 
but  which  once  evidently  were  joined  together  to  form  a  continuous 
thin  sheet  which  sjjread  over  this  region. 


Small  patches  of  coarse-grained  hornblende-granite  have  been  men- 
tioned by  Hague «  as  outcropiDing  along  the  base  of  Pogonij)  Mountain. 
Whether  this  granite  is  intrusive  or  Archean  is  not  stated. 

STRUCTURE. 

FOLDING. 

The  main  ridge,  Mokeamoke,  which  extends  north  from  the  White 
Pine  mining  district,  has  a  general  synclinal  structure.  This  sjaicline 
is  variously  affected  by  erosion,  so  that  at  times  one  limb  is  almost 
completely  worn  away,  giving  the  range  the  aspect  of  being  monocli- 
nal.  For  the  most  part,  however,  this  syncline  is  well  shown  for  a 
number  of  miles  north  of  Hamilton.  Still  farther  north,  as  far  as  the 
southern  end  of  the  Humboldt  Range,  the  structure  was  not  carefully 
observed,  but  in  general  it  consists  of  a  series  of  gentle  ojjen  folds 
trending  parallel  to  the  mountain  ridges.  On  Coal  Burners  or  Bald 
Mountain  the  attitude  of  the  strata  seems  to  be  very  near  horizontal. 

Besides  the  main  Mokeamoke  Ridge,  whose  structure,  as  sketched 
about  8  miles  north  of  Hamilton,  is  shown  in  the  accompanying  figure 

nU.  S.  Geol.  Expl.  Fprtietli  Par.,  Vol.  II,  p.  542, 

Bull,  208—03-^-5 


66 


GEOLOGY    OF    NEVADA    SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


(fig.  1),  there  are  several  minor  parallel  ridges.  North  of  the  White 
Pine  mining  district  these  minor  ridges  lie  east  of  the  main  one,  form- 
ing a   continuous  section   which  unites  Mokeamoke  Ridge  with  the 


(O-o 


flj    QO 

>  c 


-1    E 


Fig.  1.— Sketch  section  5  miles  north  of  Hamilton  across  White  Pine  Range  to  the  eastern  edge 
of  Long  Valley  Range.    (For  explanation  of  numbers  see  fig.  2.) 

southern  end  of  the  Long  Valley  Range.     These  ridges  and  the  accom- 
panying valleys  (in  whose  bottoms  the  rock  is  very  little  obscured  by 


Horizontal   and  vertical  scale 


ZOOOfeet  above  sea.  level 


Fig.  2.— Sketch  section  through  White  Pine  Range  at  Hamilton  at  the  junction  of  White  Pine 

and  Long  Valley  ranges. 

1.  Cambrian  limestones.  6.  White  Pine  shale  (Devonian). 

2.  Pogonip  limestone  (Silurian).  7.  Diamond  Peak  quartzite  (Coal  Measures). 

3.  Eureka  quartzite  (Silurian).  8.  Coal  Measures  limestone. 

4.  Lone  Mountain  limestone  (Silurian).  9.  Valley  wash  (Pleistocene). 

5.  Nevada  limestone  (Devonian). 

detritus)  expose  a  series  of  gentle  anticlinal  and  synclinal  folds  of 
similar  character  to  the  syncline  of  Mokeamoke  Ridge.  The  struc- 
ture here  is  shown  in  fig.  2. 

FAULTING. 

In  the  region  of  Hamilton,  where  the  mountains  widen  out  notice- 
ably, the  structure  of  the  rocks  west  of  Mokeamoke  Ridge  consists  in 
general  of  a  pronounced  north-south  trending  anticline,  which  afi'ects 
the  central  ridge  comprising  Treasure  Hill  and  minor  eminences,  and, 
farther  west,  a  general  syncline,  the  western  limb  of  which  is  Pogonip 


SPURR.]  WHITE    PINE    KANGE,  67 

ridge.  Within  this  region  also  there  are  a  great  number  of  faults, 
which  appear  in  general  to  belong  to  two  systems,  one  having  a 
north-south  and  the  other  an  east-west  strike.  The  heaviest  fault  of 
the  region  appeared  to  the  writer  to  be  that  at  the  northern  end  of 
Pogonip  Mountain,  where  the  Coal  Measures  limestones  are  brought 
by  a  hidden  east-west  fault  directlj^  against  the  Silurian  strata  of 
the  mountain.  This  fault,  therefore,  must  have  a  vertical  displace- 
ment of  from  7,000  to  10,000  feet.  On  the  northwest  corner  of  Pogo- 
nip IMountain  another  fault  was  observed,  having  a  considerably  less 
displacement  and  a  northwest  strike.  Mr.  Hague '^^  mentions  another 
heavy  fault  on  the  western  side  of  the  same  mountain.  Between 
Pogonip  Mountain  and  the  Treasure  Hill  ridge  there  is  also,  accord- 
ing to  Mr.  Hague, ^  a  disijlacement.  In  Treasure  Hill  itself  Mr. 
Hague '^  described,  and  the  writer  subsequently  observed,  an  east- 
west  fault  which  crosses  from  the  southern  side  of  Treasure  Hill 
to  Pogonip  Mountain.  It  apj)eared  to  the  writer  also  that  the  steeply 
bent  anticlinal  fold  which  is  exposed  in  an  east-west  cross  section  of 
Treasure  Hill  has  been  faulted  somewhat  along  its  axis  and  the  east- 
ern part  relatively  downthrust,  the  fault  being  probably  a  normal 
one.  There  are  certainly  many  other  faults  in  the  mining  district, 
but  all  the  examinations  thus  far  made  have  been  cursor}^  On  the 
western  side  of  Mokeamoke  Ridge  and  in  AUepaw  (Applegarth?)  Can- 
yon a  number  of  probable  east- west  faults  were  observed. 

It  will  be  noted  that  this  faulting  is,  so  far  as  observed,  restricted 
to  the  neighborhood  of  the  mining  district.  To  the  north  and  to  the 
south  there  is  little  reason  for  believing  that  the  mountains  are  much 
affected  by  faulting.  The  White  Pine  district,  then,  bears  exactly  the 
same  relation  to  the  rest  of  the  White  Pine  Range  as  the  Eureka 
district  does  to  the  Diamond  Range.  Both  are  areas  of  local  and 
special  dynamic  disturbance,  resulting  in  folding,  faulting,  and  ore 
deposition,  and  in  both  the  special  effects  die  out  in  a  surprisingly 
short  distance. 

RELATION  OF  TOPOGRAPHY  TO  STRUCTURE. 

In  the  northern  part  of  the  White  Pine  Range,  north  of  the  mining 
region,  there  is  a  distinct  tendency  toward  anticlinal  valleys  and 
synclinal  ridges.  The  mountains,  therefore,  though  determined  pri- 
marily by  erosion,  yet  have  the  location  of  their  ridges  and  valleys 
governed  by  the  position  of  the  folds.  South  of  the  White  Pine 
mining  region  the  same  general  peculiarities  hold  to  the  southern  end 
of  the  range. 

Within  the  mining  region  itself  the  faults  introduce  a  new  feature 
into  the  topography.     The  whole  district,  as  before  stated,  is  traversed 

«Mon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  190. 

''Ibid.,  p.  192. 

cU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  Ill,  p.  412, 


68  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.  208. 

by  a  north-south  and  an  east- west  system  of  faults,  with  minor  diago- 
nal ones.     Some  of  these  are  attended  by  steep  scarps. 

In  the  same  district  wliere  these  scarps  occur  the  folds  seem  to 
have  directly  determined  the  topograjihy.  The  Treasure  Hill  ridge 
is  anticlinal  and  the  valley  between  it  and  Pogonip  Mountain  syn- 
clinal. But  Mokeamoke  Ridge  and  the  ridges  to  the  west  are  syn- 
clinal, witli  anticlinal  valleys,  indicating  a  long-continued  erosion 
period.  The  folding  of  the  ridges  to  the  west  of  Mokeamoke  Ridge 
was  then  distinctly  later  than  that  of  the  ridge  itself  and  later  than 
that  of  the  range  in  general. 

The  faults  of  the  mining  district  appear  to  belong  also  to  the  same 
recent  epoch  as  the  associated  folds.  Those  of  Treasure  Hill  have 
apparently  been  affected  very  little  by  erosion,  and  are  marked  by 
scarps  which  seem  to  represent  very  closely  the  vertical  displace- 
ment. The  same  seems  to  be  true  of  the  heavy  fault  which  forms  the 
northern  end  of  Pogonip  Mountain,  which  has  already  been  mentioned. 

ORES. 

The  structurally  complicated  region  around  Hamilton  has  been  the 
site  of  rich  ore  deposition.  The  ores  are  distinctly  connected  with 
the  fault  fissures  and  have  formed  largely  in  their  vicinit3^  Mr. 
Hague "-  describes  the  occurrence  of  the  silver  deposits  of  Treasure 
Hill  as  (1)  in  fissures,  striking  east  and  west;  (2)  in  deposits  between 
the  limestone  and  shale;  (3)  in  beds  or  chambers  in  the  limestone 
and  parallel  to  the  stratification  of  the  rock;  and  (4)  in  the  regular 
seams  or  joints  across  the  rock  bedding,  most  frequently  with  a  north- 
south  trend.  The  minerals  found  in  the  mining  district  comjjrise 
quartzite,  calcite,  gypsum,  fluorite,  barite,  black  oxide  of  manganese, 
rhodochrosite,  cerargyrite,  galena,  cerussite,  and  azurite.  The  dis- 
trict once  had  a  population  of  many  thousand,  but  at  present  there  is 
very  little  activity. 

QUINN  CANYON  AND  GRANT  RANGES. 

The  Grant  Range  is  really  the  southern  extension  of  the  White 
Pine  Range,  there  being  no  decided  break  between  the  two.  It  has  a 
length  from  north  to  south  of  about  30  miles.  Tlie  Quinn  Canyon 
Range  is  closely  connected  with  the  Grant  Range,  being  separated 
only  by  a  narrow  rock-cut  valley,  whose  bottom  is  for  the  most  part 
comparatively  free  from  detritus.  It  is,  however,  offset  from  the 
Grant  Range  to  the  west.  The  Quinn  Canyon  Range  is  broad  and 
short,  having  a  north-south  extent  of  about  25  miles,  and  an  east- west 
extent  of  nearly  20  miles. 

TOPOGRAPHY. 

The  Grant  Range  consists  of  a  single  main  ridge,  rather  flat  and 
broad  on  toj^,  and  cut  up  deeply  by  the  smaller  mountain  valleys, 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  Ill,  p.  418 


SPURR.]  QlTIlSriSr    CANYON  AND    GRANT    RANGES.  69 

which  run  out  into  the  wide  detritus-filled  main  vallej's.  These 
smaller  valleys  and  their  auxiliary  gulches  are  generally  bounded  by 
steep  walls.  In  general,  the  main  mountain  fronts,  on  the  east  and 
west,  are  also  steep.  The  south  end  of  the  range,  which  lies  just  east 
of  Garden  Valley,  decreases  graduallj^  in  height,  and  so  passes  into  a 
series  of  low  buttes  which  run  out  into  the  valley. 

The  Quinn  Canyon  Range  is  bounded  hy  steep  cliffs  on  the  east, 
west,  and  north  sides  of  its  northern  half,  and  the  small  vallej'^s  and 
ravines  which  have  been  worn  in  this  half  are  guarded  by  the  same 
precipitous  walls  as  in  the  Grant  Range.  This  part  of  the  range  is 
cut  out  of  limestone;  hence  its  rugged  and  irregular  topograph 3^  The 
southern  part  of  the  range  is  a  mass  of  volcanic  rocks,  which,  how- 
ever, have  been  extensively  eroded.  The  type  of  topography  is  nat- 
nrally  quite  different  from  that  in  the  limestone  region,  the  distribu- 
tion of  the  valley's  being  regular  and  the  rocks  being  cut  up  into  steep 
but  not  precipitous  mountains.  The  southern  end  of  the  range  also 
appears  to  have  a  more  gradual  descent  into  the  plain  that  has  the 
northern. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

In  the  foothills  at  the  north  end  of  the  Qninn  Canyon  Rapge  and 
to  the  north  of  the  abrupt  scarj)  which  limits  the  northern  end  of  the 
mountain  proper  an  exposure  of  rustj-brown  shal}''  limestone  was 
found  in  a  canj^on,  from  which  fossils  were  collected.  They  were 
determined  by  Mr.  Walcott  as  Cambrian. 

These  were  the  onlj^  Cambrian  rocks  found  in  the  two  ranges. 
Immediately"  to  the  south,  in  the  high  mountains  of  the  Quinn  Canyon 
Range,  the  rocks  are  Silurian  and  probably  also  Devonian,  and  indeed 
an  outcrop  of  undoubtedly  Silurian  quartzite  (Eureka  formation)  was 
found  only  a  short  distance  east  of  the  Cambrian  locality.  The  atti- 
tude of  the  beds  in  both  outcroj)S  makes  it  clear  that  between  the  two 
there  is  a  heavy  fault,  and  from  the  lack  of  faulting  in  the  Quinn 
Canyon  Range  proj)er  it  is  clear  that  the  fault  does  not  run  in  a 
north-south  direction,  but  must  run  in  a  general  east-west  direction, 
not  far  from  the  base  of  the  heavj'  scarp  which  delimits  the  mountain 
at  its  north  end. 

SILURIAN. 

On  the  steep  west  face  of  the  northern  end  of  the  Quinn  Canyon 
Range  the  mountains  near  the  base  consist  of  massive,  often  shaly, 
dark-blue  to  gray-blue  limestone,  much  broken  ^.nd  veined  as  a  con- 
sequence of  granitic  intrusions.  On  account  of  the  alteration  the 
organic  remains  obtained  from  this  limestone  are  not  identifiable. 
Six  hundred  or  800  feet  above  the  base  of  the  limestone,  as  exposed, 
comes  about  200  feet  of  hard  white  vitreous  quartzite,  which  one  at 
once  recognizes  as  probably  the  Eureka  formation.  Above  this 
quartzite  comes  upward  of  4,000  feet  of  gray-blue  extremel}"  massive 
limestone,  extending  to  the  top  of  the  mountain  and  weathering  into 


70  GEOLOGY    OF    ISTEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

smooth,  perpendicular,  pinnacled  cliffs.  This  same  limestone  was 
found  all  along  the  north  end  of  the  mountain  scarp,  and  also  forms 
the  precipitous  cliffs  on  the  east  side  of  the  mountain  front,  opposite 
the  Grant  Range. 

In  some  low  foothills  on  the  northern  slope  of  this  range,  facing 
Railroad  Valley,  the  following  Ordovician  fossils  (determined  bj^  Pro- 
fessor Ulrich)  were  found  by  Mr.  F.  B.  Weeks ^'  in  1900: 

Girvanella  sp.  undet. 

Ortliis  n.  sp.  (cf.  O.  liolstoni  Safford). 

Dalmanella  perveta. 

Ortliis  tricenaria  ? 

Cf.  Strophomena  nemea  H.  &  W. 

Zygospira  n.  sp.     A  large  species,  i  inch  or  more  wide. 

Three  undetermined  brachiopods,  possibly  referrable  to  Platystrophia. 

Orthodesma  sp.  tindet. 

Lophospira. 

Cf .  Plenrotomaria  lonensis  Walcott. 

Orthoceras. 

Leperditia  (near  L.  fabulites  Conrad). 

Leperditella  sp. 

Primitia  (near  P.  celata  Ulrich) . 

BathynriTS  (1). 

Bathyuriis  (2). 

Bathynrns  (3). 

Within  the  main  range,  on  the  slopes  of  Big  Creek,  in  the  north- 
western part  of  the  range,  the  following  Ordovician  fossils  were  col- 
lected hy  Mr. Weeks,  determined  by  Professor  Ulrich: 

Receptaculites  mammilaris  Newberry. 

Receptaculites  ellipticus  Walcott. 

Plates  of  a  large  Carabocrinns  similar  to  one  occurring  in  shales  of  Blacli 

River  age  of  Minnesota. 
Plates  of  Carabocrinns  ?  with  pustulose  surface. 
Monotrypa  sp.  undet. 
Batostoma  sp.  undet. 
Ortliis  n.  sp.   (near  O.  liolstoni  Safford). 
Orthis  pogonipensis  H.&  W.  (cf.  O.  perveta). 
Ortliis  tricenaria  Conrad  (small  form). 
Orthis  lonensis  ?  Walcott. 
Maclurea  sp.  undet.  (near  M.  bigsbyi). 
Gyronema  sp.  nov.  (near  G.  semicarinatum  Salt.  sp.). 
Gen.  et  sp.  nov.  (related  to  Oxydiscus  and  Conradella). 
Orthoceras  (small  species). 

Endoceras  sp.  undet.  (with  "  Colpoceras  "  type  of  siphuncle). 
Leperditia  n.  sp.  (semipunctate). 
Leperditia  n.  sp.  (elongate  bivia). 
Leperditella  sp.  (near  germana  Ulrich) . 
Leperditella  sp.  with  ventral  swelling  in  left  valve. 
Schmidtella  n.  sp.  (near  S,  crassimarginata). 
Aparchites  sp.  undet. 
Tetradella  ?  sp.  nov. 
Cranidia  and  pygidia  of  six  (?  5)  species  of  Trilobites. 


"Personal  communication  to  the  writer. 


SPURR.]  QUINN    CAlSrYON    AND    GRANT    RANGES.  7l 

On  the  east  side  also  the  Eureka  quartzife  again  appears  and  can 
be  contiuuonsly  traced  for  long  distances,  thus  becoming  an  impor- 
tant aid  in  the  studj^  of  the  stratigraphy.  In  the  valley  which  sepa- 
rates the  Quinn  Canyon  Range  from  the  Grant  Range  the  Eureka 
quartzite  outcrops  on  both  sides,  on  the  two  limbs  of  an  anticlinal 
fold  froDi  which  the  valley  has  been  eroded.  In  the  bottom  of  the 
vallej",  beneath  the  quartzite,  is  found  massive  limestone,  brecciated, 
hardened,  and  altered.  In  the  upper  part  of  that  portion  of  the 
valley  draining  north  (which  is  separated  by  a  decided  divide  from 
that  portion  which  drains  to  the  south  into  Grarden  Valley)  the  ascent 
takes  one  above  the  horizon  of  the  Eureka  quartzite  into  that  of  the 
overlying  limestones.  Along  the  course  of  this  nortliern  j^art  of  the 
valley  no  good  fossils  could  be  found  in  any  locality,  but  fragments 
picked  up  at  various  points  in  the  canyon  have  been  identified  by 
Professor  Ulrich  as  Silurian. 

Batostoma?  sp.  iindet. 
Bathyuriis?  sp.  tindet. 
Leperditella?  sp.  nndet.     Two  species. 
Ortliis  sp.  (near  O.  holstoni  Safford). 
Ortliis  sp.  (near  O.  tricenaria). 
Receptacnlites  ellipticns  Walcott. 

At  the  divide  above  mentioned  tlie  stratified  rocks  are  hidden  ])y 
later  volcanics.  A  short  distance  south  of  the  pass,  however,  the 
Eureka  quartzite  is  again  encountered,  and  above  it  the  same  heavy 
limestone  as  appeared  in  the  Quinn  Canyon  Range.  These  rocks 
extend  quite  through  to  the  eastern  face  of  the  Grant  Range.  On 
the  lower  part  of  Cherry  Creek,  after  passing  the  volcanic  area,  dens© 
blue  limestone  is  encountered,  and  farther  down  the  Eureka  quartz- 
ite. From  the  limestone  beds,  a  few  hundred  feet  below  the  quartzite, 
the  following  Ordovician  fossils  were  obtained  and  determined  by 
Professor  Ulrich. 

Eccyliopterus  sp.  tindet. 
Encrintirns  sp.  nndet. 
Isotelns  ?. 
Lingula  sp.  nndet. 

The  Eureka  quartzite,  dipping  to  the  east,  forms  the  eastern  front 
of  the  Grant  Range  for  some  miles  north  of  Cherry  Creek,  and  then, 
on  account  of  the  irregular  erosion  of  the  mountain  front,  passes  into 
tlie  foothills,  where  it  can  be  traced  for  a  nuinber  of  miles  farther 
north. 

DEVONIAN. 

No  Devonian  fossils  were  obtained  from  either  the  Quinn  Canj^on  or 
Grant  ranges.  As  already  noted,  however,  the  thickness  of  the  lime- 
stone section  which  is  exposed  above  the  Eureka  quartzite  is  upward 
of  4,000  feet  in  both  ranges.  In  the  Eureka  section  <*  the  thickhess  of 
the  Silurian  Lone  Mountain  limestone  above  the  Eureka  quartzite  is 

aMon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  13. 


72  GEOLOGY    Oi    NEVADA   SOUTH    OF   40TH    PAEALLEL.     [bull. 208. 

given  at  1,800  feet.  There  is  an  unconformity  at  Eureka  between  the 
Eureka  quartzite  and  the  overljdng  limestone.  Nevertheless,  it  is 
very  likely  that  the  upper  portion  of  the  massive  limestone  observed 
in  the  Quinn  Canyon  and  Grant  ranges  includes  part  of  the  Devonian 
limestone  of  the  N.evada  formation. 

CARBONIFEROUS. 

On  the  eastern  slope  of  the  Grant  Range,  north  of  Warm  Spring,  in 
White  River  Valley,  the  following  Carboniferous  fossils  were  collected 
by  Mr.  F.  B.  Weeks'^  and  determined  by  Dr.  Girty: 

Chonetes  sp. 
Chonetes  illinoisensis. 
Derbya  kaskaskiensis. 
Prodtictella  ?  near  concentrica. 
Sph'ifer  centronatus. 
Camarotoechia  sp. 
Eiiinetria  verneuiliana. 
Naticopsis  sp. 
Ostracoda. 

PLIOCENE. 

In  the  northern  part  of  the  valley  separating  the  two  ranges  there 
are  found,  uj)  to  a  height  of  6,200  feet  above  the  sea,  horizontally  bed- 
ded arkoses  and  conglomerates,  made  iTp  of  the  fragments  of  the 
limestone  cliffs  above  and  nevertheless  hardened  into'  solid  rocks. 
This  may  be  a  shore  formation,  and  may  belong  to  the  Pliocene  lake 
whose  sediments  are  shown  in  the  Pancake  Range  at  Twin  Springs 
and  at  Hot  Creek.  The  Pleistocene  subaerial  accumulations  hide  the 
Tertiary  strata  throughout  the  greater  part  of  the  valleys.  A  hint  of 
the  former  existence  of  a  Pliocene  lake  on  the  west  side  of  Quinn 
Canyon  Range,  however,  was  found  in  the  x>eculiar  development  of 
the  gulches  which  furrowed  the  volcanic  rocks.  These  gulches  are 
deepest  at  the  top,  and  grow  progressively  shallower  lower  down, 
until  near  the  bottom  they  die  out  entirely.  This  may  signify  that 
the  development  of  the  gulches  began  above  the  surface  of  the  Plio- 
cene lake  and  as  the  lake  became  lower  the  gulches  were  forced  to 
extend  themselves,  but  naturally  accomplished  only  a  small  amount 
of  cutting  in  those  new  portions  as  compared  with  the  long-established 
upper  parts. 

IGNEOUS   ROCKS. 
RHYOLITE   AND   GRANITE. 

On  the  west  side  of  Quinn  Canyon  Range,  directlj^  east  of  Twin 
Springs,  are  found  great  masses  of  siliceous  igneous  rocks  which  widen 
in  extent  farther  south  and  cover  up  the  whole  of  the  range. ^  At  the 
northern  end  of  the  mountain  valley  which  separates  the  most  easterly 
part  of  the  range  from  the  westerl}^  part,  along  which  the  Quinn  Canyon 

n  Personal  communication  to  the  writer. 

I>Q.  K.  Gilbert,  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  122. 


SPURB.]  QUINN    CANYON    AND    GRANT    RANGES.  73 

road  runs,  the  volcanic  rock  has  been  stripped  down  to  the  underlying 
limestone,  which  is  found  to  be  traversed  by  great  dikes  of  acid  rock, 
varying  from  coarse  to  fine  in  texture.  The  overlj-ing  rhj^olite  and 
the  dike  rocks  were  examined  microscopically.  Of  two  specimens  of 
the  dikes  one  was  a  coarse  biotite- hornblende-granite  and  the  other 
a  very  fine  biotite-granite-porphjay,  the  same  mineralogically  as  the 
coarse  variety,  but  both  mineralogically  and  structurally  far  more 
closelj'  connected  with  the  rhj'olite.'*  It  is  probable,  therefore,  that 
the  dikes  and  the  massive  eruptions  constitute  different  jparts  of  the 
same  igneous  mass. 

BASALTIC   VOLCANICS. 

In  the  small  valley  between  the  two  ranges,  thin-bedded  basaltic 
volcanics  occur  just  south  of  the  pass  and  stretch  over  a  considerable 
area.  These  rocks  are  fine  grained  or  glassy  and  show  very  beautiful 
flow  structure,  in  strong  contrast  to  the  massive,  rugged  rhj^olite  in 
the  hills  above  them.  Specimens  examined  microscopically  show  the 
rock  to  be  a  basalt  carrying  augite  and  hornblende.  The  basaltic 
rocks  extend  for  some  distance  along  Cherry  Valley. 

QUARTZ-LATITES. 

On  the  east  side  of  the  Grant  Range,  near  the  point  where  it  joins 
the  White  Pine  Range,  the  outljnng  foothills  which  bound  the  south- 
ern or  southwestern  end  of  Sierra  Valley  are  evidently  comjDosed  of 
dark-colored  volcanic  rock.  This  is  not  far  from  similar  volcanic 
areas  which  form  the  northerly  continuation  of  the  Golden  Gate  Range, 
and  is  very  likely  of  the  same  nature.  From  one  of  the  volcanic  hills 
of  the  Golden  Gate  Range  near  this  point  a  specimen  i^roved  to  be 
quartz-latite,  containing  augite,  biotite,  and  hornblende. 

RELATIVE   AGE   OF  LAVAS. 

In  these  two  ranges  the  rhyolites  are  distinctly  oldest,  as  shown  not 
only  by  the  fact  that  the  more  basic  lavas  overlie  them,  but  also  by 
the  greater  erosion  of  the  rhj^olites  as  compared  with  the  others.  The 
latite  ax3pears  to  be  of  intermediate  age.  It  is  probable  that  the 
rhyolites  and  the  basalts  are  to  be  correlated  with  the  corresponding 
lavas  of  the  Pancake  Range,  as  exhibited  at  Twin  Springs. 

STRUCTURE. 
FOLDING. 

At  the  west  base  of  the  Quinn  Canyon  Range  the  distribution  of  the 
Eureka  quartzite  shows  that  there  exists  here  an  anticline  with  a 
north-south  or  northeasterly-southwesterly  axis.  The  north  end  of 
the  range  exposes  a  broad,  very  shallow  syncline,  which  succeeds  the 
anticline  to  the  east.  In  the  center  of  this  syncline  the  beds  are 
horizontal  for  a  considerable  distance,   and  the  maximum  dip   on 

«.J.  E.  Spurr,  Variations  of  texture  in  certain  Tertiai-y  igneous  rocks  of  the  0'*ea^  j3asin:  Jour. 
Geol.,  Vol.  IX,  1901,  p.  601. 


74 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


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the  two  sides  is  about  35°.  The  syn- 
cline  is  succeeded  farther  east  by 
an  anticline,  along  which  the  valley 
separating  the  two  mountain  ranges 
has  been  eroded.  The  Eureka  quartz- 
ite,  which  appears  on  both  sides  of 
this  anticline,  allows  its  being  traced 
easily  for  long  distances.  The  fold 
has  a  general  north  -  northwesterly 
trend  and  is  visible  in  the  moun- 
tains of  the  Grant  Range  about 
8  or  10  miles  to  the  northeast  of  the 
north  end  of  the  Quinn  Canyon 
Range.  At  this  point  it  is  much 
sharper  than  farther  south. 

The  eastern  limb  of  the  anticline, 
which  is  steeper  than  the  western 
limb,  is  at  the  same  time  the  western 
limb  of  a  syncline  which  is  dis- 
plajT^ed  in  the  Grant  Range.  There 
are  some  slight  minor  folds,  but  the 
general  cross  section  apjDcars  to  show 
a  perfect  sjnicline  at  a  point  just  east 
of  the  north  end  of  the  Quinn  Canyon 
Range.  Farther  south,  in  the  vicinity 
of  Cherrj^  Creek,  the  jutting  out  of 
the  mountains  a  little  farther  east, 
as  a  consequence  of  the  irregular  ero- 
sion, permits  the  study  of  a  third 
anticline,  Avhich  succeeds  the  syn- 
cline, and  is  a  heavy  and  persistent 
fold.  Looking  north  from  the  vicinity 
of  Cherr}"  Creek,  one  sees  this  anti- 
clinal fold  passing  from  the  side  of 
the  mountains  into  the  foothills,  so 
that  the  strata  which  at  first  dip 
easterly  on  the  mountain  face  change 
to  a  westerly  dip,  which  denotes  the 
eastern  limb  of  the  Grant  Range  syn- 
cline. These  folds  have  a  more  north- 
easterly strike  than  those  farther  west, 
so  that  the  easternmost  anticline  just 
described  probablj^  strikes  across  the 
valley  to  the  low  hills  which  divide  the 
Golden  Gate  Range  from  the  Grant 
Range  about  20  miles  north  of  Cherry 


SPURR.] 


QUINN  CANYON  AND  GKANT  RANGES. 


75 


Creek,  and  is  again  exhibited  in  the  strata  of  these  liills.  At  this 
point  the  anticline  is  joined  on  the  east  by  a  connected  series  of  open 
synclines  and  anticlines,  which  form  the  low  mountains  of  the  Golden 
Gate  Range  and  extend  across  to  the  northern  end  of  the  Hiko  Range. 


Fig.  4. 


-Sketcli  section  of  east  front  of  Grant  Eange.    Taken  5  miles  north  of  fig.  3  and  showing 
altered  position  of  anticlinal  fold  with  reference  to  the  mountain  front. 


The  strikes  of  these  folds  become  more  and  more  easterly  until  in 
the  Hiko  Range  they  swing  round  and  become  southwesterly,  and 
then,  farther  south,  pass  into  the  usual  north-south  trend  again, 
having  described  semicircles.     (See  figs.  3  and  4.) 


FAULTING. 


As  alreadj^  mentioned,  there  is  apparently  a  heavy  fault  at  the 
northern  end  of  the  Quinn  Canyon  Range,  which  has  brought  up  the 
Cambrian  rocks  on  the  north  side  against  the  Silurian  on  the  south. 
This  was  the  only  fault  determined  in  the  two  ranges.     (See  fig.  5.) 


Quinn  Canyon    Mountains 


Rai  Iroad  Valley 


Horizontal   and  vertical  scale 


Fig.  5.— Generalized  sketch  section  of  north  end  of  Quinn  Canyon  Mountains. 
1.  Silurian  limestones  and  quartzites  (probably  2.  Cambrian  limestones  and  shales. 


Devonian  on  top). 


3.  Chiefly  Pleistocene  valley  wash. 


Some  slight  crumpling  of  the  strata  was  observed  on  the  eastern  side 
of  the  Grant  Range,  near  Cherry  Creek,  but  this  was  probablj^  due  to 
the  intrusion  of  the  near-by  volcanic  rocks.  In  general,  the  folds  of 
the  stratified  rocks  are  even  and  unbroken. 

RELATION  OF  STRUCTURE  TO  TOPOGRAPHY. 


As  described,  the  Quinn  Canj^on  Range  is  essentially  a  simple  syn- 
cline,  as  is  also  the  Grant  Range.  On  the  west  side  of  the  Quinn 
Canyon  Range,  the  east  side  of  the  Grant  Range,  and  also  between 


76  GEOLOGY    OF    NEVADA    SOUTH    OF    40TH    PARALLEL,     [bull.208. 

the  two  ranges,  are  anticlines  wliicli  are  marked  by  deep  depressions. 
In  general,  therefore,  the  form  of  the  mountains  is  one  that  implies  a 
long  period  of  erosion  subsequent  to  the  folding.  Although  the  faces 
of  both  these  ranges,  on  the  east  and  on  the  west,  are  somewhat 
abrupt,  the  apparent  continuation  of  the  beds  XDast  these  steep  faces 
without  break  indicates  that  the  faces  are  not  caused  by  faulting,  but 
are  due  to  erosion.  The  north  end  of  the  Quinn  Canyon  Range  is 
probably  along  a  fault,  but  in  this  case  the  Cambrian  rocks,  which 
have  been  relatively  upthrust  by  the  faulting,  are  found  in  low  foot- 
hills running  into  the  valley,  while  the  downthrust  Silurian  rocks 
form  abrupt  cliffs  facing  the  Cambrian.  It  seems,  therefore,  that  if 
the  cliff  was  primarily  determined  by  faulting  it  is  not  directlj^  due  to 
upthrnst,  but  to  powerful  erosion. 

WORTHINGTON   MOUNTAINS. 

The  Worthington  Mountains  are  a  very  small  group  lying  north- 
west of  the  Pahranagat  Range,  with  which  they  are  connected  by  a 
series  of  hills.  They  also  are  connected  with  and  probably  form  the 
northern  extension  ef  the  Timpahute  Range,  and  on  the  north  the 
rocks  are  probably  continuous  with  those  of  the  Grant  Range,  from 
which  they  are  separated  by  a  few  miles  of  desert  valley.  On  the 
west  side  of  the  Worthington  Mountains  there  is  a  series  of  low  hills 
which  form  a  certain  connection  between  them  and  the  Quinn  Canyon 
Range. 

Like  most  of  the  high  mountains  of  the  region,  as,  for  example,  the 
Quinn  Canyon  Range  and  the  Grant  Range  farther  north,  the  Worth- 
ington Mountains  have  steep  sides,  averaging  perhaps  30°  in  incli- 
nation to  the  horizontal,  to  the  east,  west,  and  north. 

SEDIMENTARY   ROCKS. 

The  northern  end  of  the  range  was  viewed  by  the  writer  from  a  point 
several  miles  farther  north.  From  here  the  rocks  are  apparently 
massive  limestones,  resembling  the  Devonian  and  Silurian  strata  of 
the  Grant  Range  just  to  the  north,  and  having  a  similar  strike.  These 
same  strata  can  be  traced  southward  along  the  flanks  of  the  moun- 
tains. At  the  northern  end,  according  to  Mr.  Gilbert,^  they  consist 
principally  of  limestone,  with  some  sandstone-  The  limestone  carried 
abundant  fossils,  which  probably  belong  to  the  Silurian. 

IGNEOUS   ROCKS. 

According  to  Mr.  Gilbert,  the  northern  end  of  the  mountain  is 
flanked  on  the  east  by  beds  of  rhyolite,  associated  with  which  are  the 
Freiberg  silver  mines. 

nU.  S.  Geog.  Sui-v.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  37. 


spuRR.]  WOKTHINGTON    AND    PANCAKE    RANGES.  77 


STRUCTURE. 

At  tilie  northern  end  of  the  range  the  strata  dip  westerly  about  30°, 
parallel  with  the  general  slope  of  the  range.  Farther  south  the  dij) 
grows  continually  less,  until  at  the  southern  end  it  is  horizontal.  It 
was  at  this  point  observed  by  Mr.  Gilbert,  who  interpreted  the  hori- 
zontal structure  of  this  bold  mountain  as  determined  bj^  faults  on 
both  sides,  the  mountain  being  an  upthrust  block  between  the  two. 
Considering  the  change  in  attitude  between  the  south  and  north  ends, 
however,  it  may  also  be  that  the  mountain  represents  part  of  a  fold 
whose  strike  diverges  slightl}^  from  the  trend  of  the  ridge. 

PANCAKE    RANGE. 
TOPOGRAPHY. 

The  northern  end  of  the  Pancake  Range  lies  just  east  of  Eureka, 
where  it  terminates  in  White  Pine  Valley.  North  of  this  termination 
and  across  the  valley  is  Coal  Burner  or  Bald  Mountain,  a  prominent 
eminence  which  appears  to  be  in  geologic  continuity  with  the  Pancake 
Range,  but  which  is  more  closely  connected  topographically  with  the . 
southern  end  of  the  Humboldt  Range.  To  the  south  the  Pancake  Range 
extends  in  a  straggling  fashion  as  far  as  Twin  Springs,  a  distance  of 
about  100  miles,  with  a  general  trend  a  little  west  of  south.  At  Twin 
Springs  a  narrow  pass  separates  the  Pancake  Range  from  the  Reveille 
Range,  farther  south.  There  is,  however,  no  real  break  in  the  topo- 
graphic continuity  here,  and  the  distinction  is  therefore  somewhat 
arbitrary. 

The  Pancake  Range  is  low  and  without  striking  relief,  as  its  name 
indicates.  The  northern  end  of  the  range  consists  in  part  of  lime- 
stone ridges  with  general  northwest  trends,  diagonal  to  the  trend  of 
the  range.  Flanking  these  limestone  ridges  are  somewhat  dissected 
but  nevertheless  level-topped  volcanic  mesas.  South  of  the  road 
between  Eureka  and  Hamilton  is  a  considerable  area  of  shaly  Devo- 
nian rocks,  which  are  eroded  into  low  smooth  hills.  About  8  or  10 
miles  farther  south,  with  the  covering  up  of  the  stratified  rocks  by 
later  eruptives,  a  corresponding  change  in  the  topographj^  takes 
place.  The  single  main  ridge  divides  into  a  number  of  irregular 
parallel  ridges  and  the  low  smooth  hills  change  to  higher  ones  which, 
though  sometimes  rounded,  are  often  sharp  or  conical.  The  tops  of 
these  hills  often  join  to  form  a  general  mesa.  This  type  of  topog- 
raphy extends  to  the  extreme  southern  end  of  the  range. 

SEDIMENTARY  ROCKS. 

CARBONIFEROUS. 

In  the  northern  end  of  the  range  limestones  and  conglomerates  asso- 
ciated with  thin  seams  of  impure  coal  have  been  reported.'*    These 

aMon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  96. 


78  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bill  208. 

limestones  contain  numerous  species  of  Carboniferous  fossils.  The 
writer  also  collected  Upper  Carboniferous  fossils  from  tlie  vicinity  of 
the  road  which  crosses  the  Pancake  Mountains  between  Eureka  and 
Hamilton.  One  locality  afforded  the  following  species,  which  were 
determined  by  Dr.  Girtj^ : 

Fusulina  cylindrica. 
Fisttilipora  ?  sp. 
Derbya  sp. 

Chonetes  verneuilianus. 
Rhipidomella  pecosi. 
Prodtictiis  sp. 
ProtliTctiis  nebraskensis  ? 
Margin!  f  era  muricata  ? 
Seniinula  subtilita  ? 

Another  localit}^  about  2  miles  southeast  of  the  first,  yielded 
Chceietes  milleporaceus,  Spirifer  rockymontanus,  Phillijjsia  s;2>- 

These  fossils  were  in  shaly  gray  limestone,  which  was  overlain  by 
more  massive  limestone,  interstratified  with  occasional  belts  of  con- 
glomerate containing  pebbles  of  quartzite  and  chert. 

DEVONIAN. 

South  of  the  road  meiitioned  come  in  the  sandy  and  limy  shales  of 
the  Devonian  White  Pine  formation. «  This  shale  is  associated  with 
beds  of  brown  sandstone  which  contains  plant  remains. 

TERTIARY. 

On  the  west  side  of  Hastings  Pass,  in  the  Humboldt  Range,  near 
the  northern  end  of  White  Pine.  Valley,  are  sediments  to  which  was 
given  the  name  of  the  Humboldt  Pliocene,  and  which  were  described 
and  mapped  by  the  Fortieth  Parallel  Survey.  These  beds  were 
examined  by  the  writer  and  were  found  to  consist  largely  of  limestone 
fragments  derived  from  adjacent  Silurian  rocks.  They  abut  against 
the  mass  of  the  Humboldt  Range  in  such  a  manner  as  to  show  that 
this  range  formed  their  shore  line  and  that  they  were  deposits  formed 
when  the  valley  had  practically  its  present  shape. 

In  other  parts  of  the  valley  the  Pliocene  deposits  are  generally 
covered  with  Pleistocene  accumulations,  and  are  therefore  not  dis- 
cernible. Along  the  Pancake  Range,  however,  on  the  east  side  of 
the  extreme  southern  end  of  Little  Smoky  Valley,  stratified  deposits 
similar  to  those  on  the  flanks  of  the  Humboldt  Range  were  found, 
forming  a  fringe  around  the  mountains. 

At  Twin  Springs  the  canyon  which  has  been  worn  transversely  across 
the  mountains  exposes  a  section  of  Tertiary  stratified  rocks,  lying 
between  the  Tertiary  volcanics.  The  section  shows  rhyolite  at  the 
base.     Above  this  comes  several  hundred  feet  of  horizontally  bedded 

n  Mon.  U.  S.  Geol.  Survey  Vol.  XX,  Atlas  sheet  4. 


SPURR]  PANCAKE    RANGE,  79 

water-laid  semiconipacted  sandstones,  apjiarently  derived  from  the 
rlij^olite.  At  the  top  of  this  stratified  series  the  white  sands  change 
to  stratified  tufl's  and  gravels,  brown  in  color  and  evidently  derived 
from  basic  lava  snch  as  immediately  overlies  them.  This  lava  is  a 
solid  dark-colored  basalt,  which  forms  the  uppermost  member  of  the 
series. 

PLEISTOCENE   LAKE  .DEPOSITION. 

At  several  points  the  marks  of  a  comparatively  recent  body  of 
water,  occupying  a  large  part  of  Big  Smoky  and  White  Pine  valleys, 
were  observed.  On  the  east  side  of  the  Diamond  Range,  about  10 
miles  north  of  Pinto  Creek,  distinct  terraces  were  observed  in  the 
detritus  at  the  base  of  the  mountains.  These  terraces  are  several  in 
number  and  are  50  or  60  feet  above  the  valley  floor.  Also  about  15 
miles  south  of  Fish  Creek  a  regular  bench  com  loosed  of  lava  debris 
was  noted  on  both  sides  of  the  vallej^  about  15  feet  above  the  smooth 
mud  deposits  of  the  valley  bottom.  Farther  north,  at  a  point  on  the 
Pancake  Range  just  south  of  the  road  between  Eureka  and  Hamilton, 
at  the  mouth  of  a  gap  in  the  hills,  a  definite  beach  bar  was  noticed, 
such  as  forms  along  gently  sloping  shores  at  the  mouths  of  inlets. 

There  was  therefore  probably  a  Pleistocene  body  of  water  which 
spread  over  the  greater  part  of  Little  Smoky  and  White  Pine  valleys. 
The  shore  marks  above  mentioned  indicate  that  this  lake  was  shallow. 
Tlie  final  remains  of  the  Pleistocene  lake  may  be  considered  as  still 
existing  in  the  numerous  marshy  ponds  which  are  scattered  through 
the  White  Pine  Valley  north  of  the  Pancake  Range. 

GULCH  DUMPS  OR  ALLUVIAL  FANS. 

Along  the  line  of  junction  of  the  mountains  Avitli  the  valleys,  and 
occasionally  forming  the  low  foothills,  are  sometimes  observed  accu- 
mulations of  detritus  which  rise  above  the  level  valley  floor,  and 
which  have  such  relation  to  the  gulches  of  the  mountains  above  that 
it  is  plain  their  materials  have  been  derived  from  their  erosion;  and 
in  some  cases  it  seems  that  the  amount  of  material  in  these  dumps  is 
a  verj^  large  portion  of  that  which  has  been  removed  in  the  excava- 
tion of  the  gulches.  Where  this  material  is  exposed  at  the  surface,  it 
is  found  to  be  angular  and  bearing  other  marks  of  having  been 
brought  down  by  torrents. 

These  accumulations  are  certainly,  in  part  at  least.  Pleistocene,  and 
are  being  added  to  at  i^resent.  However,  they  antedate  largely  the 
Pleistocene  water  body  above  described.  They  are  therefore  Pliocene- 
Pleistocene,  and  are  largely  contemporaneous  with  the  water-laid 
deposits  which  occur  at  lower  altitudes. 

IGNEOUS  ROCKS. 

At  the  northern  end  of  the  Pancake  Range  a  body  of  rhyolite  forms 
the  western  half  of  the  mountains  and  extends  as  far  south  as  the 


80  GEOLOGY    OF    NEVADA   SOUTH    OF    40X11    PARALLEL.     [buli^.S-K. 

road  between  Eureka  and  Hamilton.  A  short  distance  south  of  this 
road  andesite  comes  in  in  considerable  patches/'  This  andesite  was 
observed  by  the  writer  at  intervals  for  a  distance  of  10  or  15  miles 
south  of  here.  It  is  here  generally  mixed  up  with  small  areas  of  rhyo- 
lite.  Still  farther  south  rhyolite  seems  to  form  the  greater  part  of 
the  range  (PL  V,  B).  In  the  neighborhood  of  Twin  Springs,  as  men- 
tioned above,  the  rhyolite  occurs  at  the  base  of  the  section  and  basalt 
at  the  top. 

STRUCTURE. 

FOLDING. 

The  area  of  White  Pine  Devonian  rocks,  above  described,  forms  a 
shallow  syncline  which  apparently  gives  place  to  a  gentle  anticline 
farther  north,  and  there  exposes  the  Carboniferous  limestones.  It  is 
possible,  however,  that  it  is  a  fault  which  brings  up  these  limestones. 
The  syncline  has  a  general  northwest  strike  and  is  i)lainly  continuous 
with  the  faulted  syncline  of  the  Eureka  district,  just  across  the  valley, 
which  has  Newark  Mountain  on  its  eastern  limb  and  the  Alhambra 
Hills  on  its  western.  This  syncline  may  be  traced  across  the  Pancake 
Mountains  and  across  the  intervening  low  hills  to  the  White  Pine 
Range,  its  strike  being  at  an  angle  to  the  general  trend  of  the  major 
ridges,  although  the  minor  ridges  conform  to  it. 

FAULTING. 

The  Upper  Carboniferous  limestones  on  the  road  across  the  range, 
between  Eureka  and  Hamilton,  have  perhaps  been  brought  to  their 


Horizontal  Scale 
I 2 smiles 


Fig.  6. — Generalized  sketch  cross  section  of  Pancake  Range  at  north  side  of  pass  at 

Twin  Springs. 

1.  Rhyolite,  200  feet.  i.  Olivine-basalt,  200  feet. 

2.  Rhyolite  sandstone,  600  feet.  5.  Valley  wash  (Pleistocene). 

3.  Basaltic  tnffs  and  gravels,  100  feet.  6.  Faults. 

present  jDosition  by  an  east-west  fault,  transverse  to  the  trend  of  the 
range,  for  their  relation  to  the  Devonian  rocks  just  south  of  here  can 
not  be  readily  explained  by  the  folding. 

The  accompanying  section  (fig.  6)  shows  the  structure  of  the  Pan- 
cake Mountains  at  Twin  Springs.  There  has  been  practically  no 
folding  here,  except  where  the  beds  have  been  locally  crumpled  bj^ 
overriding  sheets  of  lava.  A  series  of  faults  was  observed,  some  of 
which  have  a  throw  of  several  huudi-ed  feet.  The  fault  lines  are 
accompanied  by  gullies,  but  not  by  fault  scarps. 


«  gee  Mon,  U,  S,  Geol,  Survey  Vol.  XX,  Atlas  sheet  4. 


1 


spuRR.]  PANCAKE    AND    DIAMOND    KANGES-  81 

COAL. 

lu  the  northern  end  of  the  Pancake  Range  the  Carboniferous  rocks 
carry  tliin  seams  of  impure  coal,  which  have  been  in  vain  explored 
for  marketable  material.  "■ 

DIAMOND   RANGE. 

The  Diamond  Range  may  be  somewhat  arbitrarily  defined  as  begin- 
ning at  Railroad  Canyon  on  the  north,  and  extending  southward 
through  the  Eureka  Mountains  to  Fish  Creek.  South  of  Fish  Creek 
comj^aratively  low  mountains  occur.  No  decided  break  separates 
these  from  the  Eureka  Mountains,  but  they  are  more  closely  associ- 
ated with  the  Hot  Creek  Range,  and  will  be  described  in  the  latter 
connection. 

TOPOGRAPHY. 

The  main  part  of  the  Diamond  Range,  from  its  northern  end  to  the 
vicinity  of  Eureka,  consists  of  a  single  narrow,  somewhat  regular 
ridge,  whose  divide  is  in  the  center.  This  is  sharply  cut  uj)  on  both 
sides,  so  as  to  present  a  succession  of  well-defined  peaks,  with  deep 
drainage  channels. 

In  the  neighborhood  of  Eureka  this  simple  topographic  structure 
changes  to  a  more  complicated  one,  which  is  the  expression  of  a 
geologic  structure  more  comj^licated  than  that  to  the  north.  The 
mountains  in  the  vicinity  of  Eureka  are  considerabl}^  folded,  and  are 
traversed  by  numerous  faults,  which  run  in  several  directions.  The 
result  of  the  erosion  of  this  structurally  complicated  region  is  that 
there  have  arisen  many  separate  mountain  ridges,  and  the  total  width 
of  the  range  has  increased. 

South  of  the  Eureka  Mountains  the  range  is  composed  of  a  single 
narrow  ridge  of  stratified  rocks,  which  seem  to  resume  the  compara- 
tively" simple  structure  of  the  northern  portion.  Just  south  of  here 
the  sedimentaries  are  buried  iinder  thick  sheets  of  lava. 

SEDIMENTARY    ROCKS. 

At  the  nothern  end  of  the  Diamond  Range,  at  Railroad  Canyon, 
the  rocks  have  been  described  by  Mr.  Hague  ^  as  light  cream-colored 
limestones  dipping  to  the  north  under  sheets  of  basalt.  These  lime- 
stones are  mapped  by  the  Fortieth  Parallel  geologists  ^  as  the  Lower 
Coal  Measures. 

The  writer  traveled  along  the  easterly  face  of  the  Diamond  Range, 
from  a  i)oint  just  west  of  Hastings  Pass,  in  the  Humboldt  Range,  to 
the  southern  termination.     At  the  northern  end  of  the  traverse  a  sec- 

aMon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  95. 

b  U.  S.  Geol.  Espl.  Fortieth  Par.,  Vol.  II,  p.  5i9. 

fldem,  Atlas,  map  4,  west  half. 

Bull.  20S— 03 G 


82  GEOLOGY    OF    NEVADA    SOUTH    OF    -lOTH    PARALLEL,     [bull.308. 

tion  of  strata  is  visible,  wliicli,  in  default  of  oj)i30i-tiinity  for  examina- 
tion, Avas  provision allj^  supposed  to  have  the  Devonian  White  Pine 
shale  of  Eureka  at  the  base,  with  the  Carboniferous  Diamond  Peak 
quartzite  above. 

The  thickness  of  the  exposures  of  these  two  formations  was  roughly 
estimated  at  from  2,000  to  2,500  feet.  Above  this  section  were 
obsei'ved  comparatively  massive  limestones  which  were  taken  to  be 
the  Lower  Coal  Measures  limestones,  and  of  these  an  estimated  thick- 
ness of  4,000  feet  was  observed.  Above  these  again  are  heavy 
brown-weathering  massive  rocks  forming  the  precipitous  crest  of  the 
range  for  a  long  distance.  These  were  thought  to  belong  to  the  Webtr 
formation.  About  1,500  feet  of  this  was  visible,  the  top  not  being 
seen.  Mr.  Hague  ^*  notes  that  at  Chokup  Pass,  which  is  within  the 
above  section,  limestones  occur  in  which  no  fossils  were  found.  "In 
the  limestone  occurs  a  belt  of  coarse,  although  compact,  brownish- 
yellow  sandstone,  not  unlike  the  sandstone  body  at  White  Pine,  which 
lies  at  the  base  of  the  Coal  Measures  limestone.  It  measures  nearly 
300  feet  in  thickness."  This  is,  perhai^s,  the  Diamond  Peak  quartz- 
ite, as  it  was  afterwards  called  bj^  the  geologists  who  studied  the 
Eureka  district. 

South  of  Chokup  Pass  the  same  formations  occur.  In  the  eastern 
foothills  the  Diamond  Peak  quartzite  outcrops,  brown,  iron  stained, 
friable,  and  calcareous,  resembling  exactly  the  same  formation  as 
exposed  in  the  Egan  Range,  in  the  canyon  west  of  Ely.  The  quartzite 
becomes  at  times  a  conglomerate,  containing  i^ebbles  of  chert  and 
limestone.  It  is  possible  that  this  conglomerate  indicates  an  erosion 
interval  between  the  Carboniferous  and  the  underlying  Devonian. 

A  few  miles  farther  south,  the  strike  of  the  Diamond  Peak  quartz- 
ite having  carried  it  temporarily  under  the  valley  detritus,  the 
eastern  foothills  are  composed  of  the  overlying  dark-blue  limestone 
with  chert  nodules.  This  limestone  cai-ries  the  following  abundant 
fauna,  determined  as  Upper  Carboniferous  by  Dr.  Girty; 

Fistulipora  ?  sp. 
Rhombopora  lepidodeiidroides. 
ArchaBOcidaris  sp. 
Productns  prattenianus. 
Prodiicttis  semireticulattis. 
Productus  nebraskensis. 
Prodnctus  nevadensis  ?. 
Sph'ifer  boonensis. 
Seminula  stibtilita. 
Fish  scale. 

Still  farther  south  a  change  in  the  structure  brings  in  the  Diamond 
Peak^iuartzite  again,  together  with  the  underlying  Devonian  rocks, 
and  the  strata  rise  rapidly  to  the  top  of  the  range. 

In  Chihuahua  Canyon,  which  lies  to  the  east  of  Diamond  Peak, 

n  U.  S.  Geol.  Expl.  Fortieth  Par.,  Atlas,  map  4,  west  half. 


spuRR]  DIAMOND    KANGE.  83 

slightly  fetid  limestone  was  found,  and  at  a  point  about  1,000  feet 
above  the  bottom  of  the  series  exjDosed  were  Devonian  fossils,  as 
determined  by  Dr.  Girty. 

Ampliipora  ?  sp. 
Spirifer  engelmanni. 
Spirifer,  indeterminable. 
Spirifer  uiaia  (small  variety)  ?. 
Atrypa  missouriensis. 

This  is  part  of  the  Nevada  limestone,  for  the  Devonian  White 
Pine  shales  come  in  about  500  feet  above. 

South  of  here  the  geology  has  been  thoroughly  worked  out  during 
the  surve}^  of  the  Eureka  mining  district,  which  survey  embraces  the 
region  from  Diamond  Peak  on  the  north  to  White  Cloud  Peak  on  the 
south. 

Within  this  area  is  found  exposed  the  best  Paleozoic  section  yet 
studied  west  of  the  Rocky  Mountains,  comprising  strata  from  the 
Prospect  Mountain  Cambrian  quartzite,  through  the  Cambrian,  Silu- 
rian, Devonian,  and  Carboniferous.^ 

South  of  the  Eureka  mining  district  proper,  the  single  ridge  into 
which  the  mountains  contract  is  shown  in  the  geologic  maj)  of  the 
Eureka  district^  to  be  composed  of  the  Silurian  Pogonip  limestone. 
This  limestone  extends  farther  south  till  covered  up  by  volcanic  flows. 

IGNEOUS  ROCKS. 

At  the  northern  termination  of  the  Diamond  Range  the  stratified 
rocks  are  overlain  by  flows  of  basalt. '^  Between  this  point  and  the 
region  around  Eureka  no  igneous  rocks  were  observed.  The  Eureka 
district,  however,  lias  been  the  seat  of  volcanic  activity.  Among  the 
volcanic  rocks,  hornblende-andesite,  dacite,  rhyolite,  pyroxene-ande^ 
site,  and  basalt  have  been  described  bj'^  Mr.  Iddings.*^  Granite-i^or- 
phyry  is  also  found  as  a  dike  rock. 

The  volcanic  rock  which  occurs  at  the  southern  termination  of  the 
range  has  been  determined  by  the  writer,  a  few  miles  farther  south, 
to  be  rhyolite. 

STRUCTURE. 

North  of  the  Eureka  district  the  stratified  rocks  of  the  Diamond 
Range  are  bent  into  a  series  of  gentle  folds  which  in  general  strike 
nearl}^  with  the  trend  of  the  range.  In  the  region  between  Chokup 
Pass  and  Railroad  Pass  these  folds  seem  to  consist  of  an  anticline  on 
the  east  side,  with  its  eastern  limb  almost  buried  by  the  detritus  of 
the  valley,  followed  by  a  shallow  broad  syncline  to  the  west,  and  this 

« Arnold  Hague,  Geology  of  the  Eureka  district,  Nevada:  Mon.  U.  S.  Geol.  Survey  Vol.  XX; 
C.  D.  Walcott,  Paleontology  of  the  Eureka  district:  Mon.  U.  S.  Geol.  Survey  Vol.  VIII. 
&Mon.  U.  S.  Geol.  Survey  Vol.  XX,  Atlas  sheet  4. 
c  Arnold  Hague,  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  549. 
dMon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  233  et  seq. 


84  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 308. 

in  turn  by  an  important  anticline  wliicli  seems  to  form  tlie  western 
edge  of  the  mountains. 

At  Chokup  Pass  Mr.  Hague"  notes  tlie  general  anticlinal  structure 
of  the  mountains,  the  summit  of  the  anticline  occupj-ing  the  crest  of 
the  pass.  This  is  the  same  anticline  as  has  just  been  noted  as  form- 
ing the  western  face  of  the  mountains  to  the  north  of  the  pass,  the 
slight  divergence  of  the  strike  of  the  fold  from  the  trend  of  the  moun- 
tain bringing  the  fold  to  this  place.  Farther  south  the  continued 
divergence  brings  the  axis  of  this  anticline  at  one  point  down  to  the 
easternmost  foothills.  As  a  consequence  of  this,  the  syncline  and 
anticline  which  lie  to  the  east  are  covered  by  valley  detritus.  Farther 
south  still,  as  one  approaches  the  vicinity  of  Diamond  Peak,  the  trend 
of  the  folds  changes  slightly  and  again  brings  the  crest  of  the  eastern- 
most anticline  to  the  summit  of  the  range. 

South  of  Diamond  Peak  the  country  in  the  neighborhood  of  Eureka 
is  a  region  of  special  dynamic  disturbance,  and  is  folded  and  faulted 
to  a  remarkable  degree.  Except  in  this  district,  however,  no  faults 
have  been  observed  in  the  range. 

RELATION    OF   STRUCTURE   TO   TOPOGRAPHY. 

North  of  the  Eureka  district  the  structure  has  been  so  far  influ- 
ential that  the  trend  of  the  range  corresponds  nearly  to  the  general 
strike. 

In  the  Eureka  district  the  complicated  topography  is  dependent 
upon  the  increased  complications  in  the  geology,  but  the  forms  appo^ir 
to  be  directly  due  to  differential  erosion.  Most  of  the  faults  here  are 
oblique  to  the  general  trend  of  the  range.  Along  these  faults  valleys 
or  canyons  are  sometimes  found,  and  sometimes  moderate  scarps; 
but  that  these  latter  are  due  to  differential  erosion  is  shown  by  the 
fact  that  it  is  sometimes  the  downthrown  side  of  the  fault  that 
appears  as  a  scarp  and  sometimes  the  upthrowu,  depending  upon  the 
nature  of  the  beds. 

ORES. 

The  whole  district  around  Eureka  has  been  the  site  of  abundant 
ore  deposition,  a  phenomenon  plainly  connected  with  the  dynamic 
disturbances  which  have  brought  about  the  complicated  folding  and 
faulting  (and  indirectly  the  topography)  and  with  the  volcanic  out- 
bursts. The  ore  deposits  of  Eureka  have  already  been  thoroughly 
studied.*  Outside  of  this  region  the  range  is  not  remarkably  ore 
bearing. 

HOT  CREEK  RANGE. 

The  Hot  Creek  Range  is  separated  at  its  south  end  by  a  narrow 
pass  from  the  Kawich  Range,  which  otherwise  is  continuous  with  it. 

aU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  549 

&J.  D.  Curtis,  Silver-lead  deposits  of  Eureka:  Mon.  U.  S.  Geol  Survey  Vol.  VII;  Arnold 
Hague,  Geology  of  the  Eureka  district:  Mon   US  Geol  Survey  Vol.  XX. 


SPURR.] 


HOT    CREEK   EANGE.  85 


From  here  it  runs  north  70  miles  and  disappears  in  a  valley  a  few 
miles  sonth  of  the  latitude  of  Eureka.  In  the  same  line,  farther 
north,  occurs  the  Piiion  Range.  The  northern  continuation  of  the 
Hot  Creek  Valley  divides  the  mountains  into  an  east  and  a  west  half. 
The  western  half  is  the  continuation  of  the  Hot  Creek  Range  proper, 
while  the  eastern  one  runs  north  and  joins  the  Eureka  Mountains. 

SEDIMENTARY   ROCKS. 
SILURIAN. 

At  the  eastern  end  of  the  canyon,  at  Hot  Creek,  the  following  sec- 
tion was  observed,  beginning  with  the  bottom: 

Section  at  Hot  Creek. 

Feet. 

1.  Tliin-bedded.  dark-blue  frosty-lustered  limestone,  calcite- veined,  with 

impei'f ect  fossil  remains 400 

2.  Massive  white  quartzite .-  400 

3.  Thin-bedded  daik-blne  limestone 200 

4.  Shales  mixed  with  thin-bedded  limestone 1 ,  000 

5.  Massive  light-gray  coarsely  crystalline  limestone,  constituting  the  top  of 

the  mountain .- .-. 500 

.  Three  miles  west  of  this  localit}^,  at  the  ranch  near  Hot  Springs, 
there  comes  in,  below  bed  No.  1,  more  massive  siliceous  light-gray, 
coarsely  crystalline  or  aphanitic  limestone  about  600  feet  in  thick- 
ness. This  makes  about  1,000  feet  of  limestone  in  all  below  the 
quartzite. 

From  the  first-named  locality,  at  a  point  about  200  feet  below  the 
quartzite,  Ordovician  fossils  were  obtained.  The  following  were  deter- 
mined by  Professor  Ulrich : 

Amphion  (sp.  near  A.  salteri  Billings) . 

nisenus  (sp.  near  I.  americanus,  consimilis.  and  crassicauda) . 

Bathynrns  sp.  iindet. 

Leper ditia  bivia  White. 

Leperditia  n.  sp. 

Aparchites  sp.  tindet. 

Primitia  (sp.  near  P.  celataUlr.). 

Primitia  (?  Enrychilina)  n.  sp. 

Enrychilina  (near  E.  snbaeqiiata)  Ulr. 

Schmidtella  n.  sp. 

ThlipsnraV  n.  sp. 

Modiolopsis  occidens,  Walcott. 

Macltirea. 

Tetranota  (n.  sp.  near  T.  obsoleta  Ulr.). 

Lophospira  (cfr.  medialis  Ulr.). 

Plenrotomaria  ?  lonensis  Walcott. 

Triptoceras  sp.  undet. 

Orthis  n.  sp.  (near  O.  holstoni  Safford). 

Dalmanella  pogonipensis.  H.  and  W. 

Batostoma,  sp.  undet. 


86  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

It  is,  then,  plain  that  the  quartzite  is  the  Eureka  quartzite  of  the 
Eureka  section,  while  the  limestone  below  corresponds  to  the  Pogonip 
formation  and  that  above  to  the  Lone  Mountain.  We  have  here 
a  section  of  about  3,100  feet  of  Silurian  rocks,  comprising  1,000  feet 
of  the  Pogonip,  400  feet  of  the  Eureka,  and  1,700  feet  of  the  Lone 
Mountain. 

A  few  miles  south  of  the  above  locality,  in  the  next  canj^on  to  the 
south  of  Hot  Creek,  there  were  collected  from  the  limestones  above 
the  quartzite  the  following  Upper  Silurian  fossils  (Niagara  ?),  as  deter- 
mined by  Professor  LTlrich: 

Halysites  catenulatus,  large  variety. 
Halysites  catenulatus,  small  variety. 
Favosites  (ramose  species). 
Syringopora  sp.  iindet. 
Amplexus  sp.  nndet. 
Cyathophyllum  sp.  undet. 
Zaphrentis  ?  sp.  undet. 
Rhynchonella  sp.  xindet. 

At  Tybo,  about  15  miles  south  of  Hot  Creek,  and  also  on  the  east 
side  of  the  range,  the  rocks  appear  to  be  mainly  massive  dark-blue 
limestones  with  a  general  westerly  dip.  This  locality  was  not  visited, 
but  a  single  fossil  obtained  from  these  limestones  was  regarded  by 
Dr.  Girty  as  jjrobably  Ordovician,  Maclurea  aymulata  ? 

From  Tybo  to  the  south  end  of  the  range,  just  west  of  Twin  Springs, 
in  the  Pancake  Range,  the  east  half  of  the  mountains  is  entirely  com- 
posed of  similar  limestones.  At  the  extreme  south  end  the  limestones 
are  overlapped  by  the  rhyolites  of  the  Kawich  Range,  which  have 
altered  the  sedimentary  rocks.  No  fossils  were  found  at  this  point, 
but  a  specimen  of  the  limestone  was  seen  under  the  microscope  to  be 
made  up  of  tinj^  indeterminable  organic  remains. 

TERTIARY. 

On  the  eastern  side  of  the  range,  extending  from  Hot  Creek  a  num- 
ber of  miles  in  both  directions,  are  gray  hills  composed  of  partly 
consolidated  coarse  gravel  and  grit.  This  material  often  overlies 
rhyolite,  from  which  it  is  partly  derived,  and  it  rests  against  the  steep 
eroded  base  of  the  limestone  mountains.  The  material  is  evidently 
waterlaid.  The  same  formation  stretches  southward  and  is  visible 
near  Tj^bo  as  a  strip  of  yellow  dissected  hills.  At  the  pass  between 
the  Hot  Creek  Range  and  the  Kawich  Range  are  large  amounts  of 
horizontally  stratified  white  waterlaid  deposits  composed  of  rhyolitic 
fragments.'^' 

This  formation  is  evidently  the  same  as  described  in  the  neighbor- 
hood of  Twin  Springs,  in  the  Pancake  Range,  a  few  miles  to  the  east. 

aThis  formation  is  chiefly  included  under  the  color  for  volcanic  rocks  on  the  map.  The  nar- 
row atrip  near  Tybo  is  not  represented. 


spuRR.J  HOT    CREEK   RANGE.  87 

IGNEOUS   ROCKS. 


The  whole  north  end.  of  the  Hot  Creek  Range,  beginning  with  a 
point  a  few  miles  north  of  Hot  Creek,  is,  so  far  as  known,  composed 
entirely  of  volcanic  rocks,  including  both  rhyolite  and  basalt.  There 
has  been  much  erosion  since  the  outpouring,  resulting  in  the  carv- 
ing of  considerable  valleys  and  the  formation  of  large  gulch  dumps 
(alluvial  fans)  at  their  mouths,  exactly  as  in  the  case  of  the  stratified 
rocks.  In  jilaces,  also,  erosion  has  stripped  away  the  upper  layers  of 
lava  and  ash  and  has  exposed  symmetrical  volcanic  cones,  which  have 
been  preserved  by  this  protecting  covering.  PI.  V,  .B,  is  aphotograi)h 
of  such  a  cone.  The  number  of  these  small  cones  and  the  abundance 
of  ash,  together  with  the  thinness  of  the  lava  sheet,  show  that  the 
volcanic  rock  in  this  region  came  from  many  separate  explosive 
vents. 

In  the  neighborhood  of  Hot  Creek,  as  before  stated,  the  eastern  half 
of  the  range  contains  a  considerable  area  of  Silurian  rocks.  However, 
rhyolile  is  found  at  the  extreme  eastern  base,  and  the  whole  western 
half  of  the  mountain  at  this  point  is  composed  of  several  thousand 
feet  of  the  same  rock.  From  here  to  the  southern  end  of  the  range 
the  western  part  is  of  volcanic,  while  the  eastern  half  is  mostly  strat- 
ified. At  the  southern  end  the  rh3^olite  mantles  around  to  the  east  to 
join  the  lava  of  the  Kawich  Range. 

STRUCTURE. 

In  Hot  Creek  Canyon  the  Silurian  rocks  form  an  anticlinal  fold, 
broken  by  two  or  three  normal  easterly  dipping  faults.  The  first  of 
these  faults  occurs  at  the  eastern  end  of  the  canyon,  and  by  it  the 
strata,  including  the  P^ureka  quartzite,  are  down-fanlted  to  the  east 
200  or  300  feet.  This  fault  was  also  noted  in  the  first  canyon  south  of 
Hot  Creek.  Three  miles  farther  west  occurs  a  second  parallel  fault. 
This  fault  has  a  vertical  separation  of  about  1,000  feet,  as  marked  by 
the  Eureka  quartzite,  upthrown  on  the  west.     (See  fig.  7.) 

From  Hot  Creek  to  the  southern  end  of  the  range  the  structure  was 
not  carefulljr examined,  but  for  nearly  the  whole  way  the  limestones 
can  be  seen  to  dip  in  general  westerly  at  an  angle  of  from  15°  to  20°. 
It  is  probable  that  this  dip  represents  the  westerly  limb  of  the  anti- 
clinal fold  exi:)osed  in  Hot  Creek  Canj^on. 

ORES. 

Along  Hot  Creek  Canyon  are  some  vertical  zones  in  which  rich  pock- 
ets of  ore  are  said  to  have  been  found.  These  zones  are  apparently 
ancient  channels  of  the  hot  springs,  which  still  exist.  South  of  this 
jDoint  the  rocks  are  more  or  less  mineralized  all  the  way  toTybo,  where 
there  are  some  important  ore  deposits. 


GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


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PINON    RANGE. 

The  Pinon  Range  is  mentioned  in 
this  report  only  because  its  southern 
end,  wliieh  extends  beyond  the  south- 
ern limit  of  the  Fortieth  Parallel 
maps,  is  included  in  the  accompany- 
ing map.  The  writer  did  not  visit 
this  range,  and  the  following  slight 
summarj^  is  taken  chiefly  from  the 
work  of  the  Fortieth  Parallel  geol- 
ogists. 

TOPOGRAPHY. 

The  range  consists  of  a  single  main 
ridge,  which  is  conspicuous  north  of 
the  fortieth  parallel  and  lies  next 
west  of  the  Humboldt  Range.  Far- 
ther south  the  Diamond  Range  comes 
in  between  the  two.  Near  this  x)oint 
the  Pinon  Range  becomes  lower,  and 
its  trend  changes  from  south  to  south- 
easterlj^  so  that  it  swings  around 
and  joins  the  Diamond  Range  near 
Eureka. 

SEDIMENTARY   ROCKS. 

In  the  neighborhood  of  Pinto  Peak 
there  is  exposed  a  thickness  of  about 
14,000  feet  of  sedimentary  rocks, ^ 
comprising  a  section  from  the  Cam- 
brian up  into  the  Carboniferous. 
South  of  this  the  range  is  almost  en- 
tirely composed  of  Devonian  rocks. 
These  Devonian  rocks  are  continu- 
ous southward  to  the  junction  with 
the  Eureka  Mountains.*^ 

IGNEOUS   ROCKS. 
VOLCANIC   ROCKS. 

Throughout  most  of  the  extent  of 
the  range  various  volcanic  rocks  are 
found,  both  at  the  east  and  the  west 
bases. 


"Arnold  Hague,  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  554. 

''Arnold  Hague,  Geology  of  the  Eureka  district:  Mon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  300. 


SPUKK]  PINON,   MONITOR,    AND    WALWEAH    RANGES.  89 

STRUCTURE. 

As  stated  by  Mr.  Hague/'  the  range  consists  of  open  anticlinal  and 
s.vnclinal  folds.  South  of  Pinto  Peak  the  structure  is  anticlinal,  the 
axis  of  the  fold  striking  diagonally  across  the  range  S.  25°  E., 
while  the  general  trend  of  the  range  at  this  point  is  west  of  south.  It 
is  likely  that  the  main  anticlinal  fold  of  the  Diamond  Range  is  the 
direct  continuation  of  this  anticline.  Farther  south,  along  the  Piiion 
Range,  this  anticline  gives  way  to  an  adjacent  sjnicline,  and  farther 
south  again  the  eastern  limb  of  this  s^nicline  is  cut  off  by  the  ^"alley, 
so  that  only  the  western  or  easterl}^  dipping  limb  remains.  This  por- 
tion of  the  range,  therefore,  has  the  aspect  of  being  monoclinal. 

A  section  made  b}^  Mr.  Walcott,*  at  Ravens  Nest,  just  north  of 
Pinto  Peak,  shows  the  structure  as  a  faulted  anticline. 

MONITOR    RANGE. 

The  Monitor  Range  is  a  belt  of  mountains  about  70  miles  long,  Ijdng 
next  west  of  the  Hot  Creek  Range.  It  has  its  northern  end  just 
south  of  the  area  shown  on  the  Fortieth  Parallel  maps.  The  northern 
part  of  the  range,  up  to  within  a  few  miles  of  Altoona  Pass,  has  the 
aspect  of  a  great  west-sloping  table  which  ends  in  a  scarp  on  the 
west,  facing  the  vallej^.  At  Altoona  Pass  the  range  is  narrower  and 
has  a  very  sharp  summit,  with  a  steep  descent  on  both  sides.  Farther 
south  the  range  grows  lower  and  is  broken  b}^  frequent  gaps,  till  it 
passes  into  low  volcanic  hills  and  dies  out  in  the  Ralston  Desert. 

Gilbert^  has  observed  a  single  spur  of  metamorphic  rock  on  the  west 
side  of  the  range  at  its  southern  end.  Otherwise  the  whole  southern 
part  of  the  range,  as  observed  by  Mr.  Gilbert  and  the  writer,  is  vol- 
canic. At  Altoona  Pass  the  lava  is  a  siliceous  rhyolite  like  that  of 
the  Hot  Creek  Range. 

It  is  probable  that  this  range  has  been  formed  b}^  a  series  of  vol- 
canoes along  a  north-south  line.  The  topograph}^  of  the  southern 
part  of  the  range  (like  that  in  the  southern  parts  of  the  Toquima  and 
Pancake  ranges)  is  extremel}"  irregular,  consisting  in  part  of  inter- 
rupted mesas  and  ancient  volcanic  cones  defaced  by  erosion.  It  is 
plain  from  this  topography  that  the  lavas  have  escaped  from  many 
different  vents  and  have  flowed  together.  Erosion  of  the  lava  has 
gone  on  to  a  considerable  extent,  indicating  the  lapse  of  some  time 
since  the  cessation  of  volcanic  activitj-. 

WAHWEAH    RANGE. 

The  name  Wahweah  Range  is  applied  to  an  irregular  cluster  of  hills 
west  of  the  southern  end  of  the  Piiion  Range  and  just  witliin  the 

"U.S.Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  5.51. 
*  ''  Men.  U.  S.  Geol.  Siirvey  Vol.  XX,  p.  2(11. 

e\J.  S.  Geog.  Surveys  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  121. 


90  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. -08. 

northern  limits  of  the  accompanyiDg  map.  It  was  not  visited  bj^  the 
writer,  and  the  following  brief  characterization  is  taken  from  the 
reports  of  the  Fortieth  Parallel  Survey: 

The  range  is  about  30  miles  long  and  at  its  northern  end  consists 
mainly  of  granite,  together  with  a  heavy  body  of  qnartzite,  which  was 
referred  to  the  Ogden  Devonian  on  lithologic  grounds,  there  being  no 
fossils.  The  sedimentary  rocks  are  here  flanked  by  flows  of  volcanics, 
which  farther  south  mantle  over  the  stratified  rocks  and  constitute 
most  of  the  surface,  exposingthe  underlying  Paleozoic  only  in  patches. '^ 

TOQUIMA  RANGE. 

The  Toquima  Range  is  situated  next  west  from  the  Monitor  Range. 
It  has  a  trend  a  little  east  of  north  and  a  total  length  of  about  80 
miles.  At  its  north  end  it  passes  into  the  level  desert  east  of  Austin, 
and  its  south  end  is  situated  southwest  of  Belmont,  on  the  borders  of 
Ralston  Valley.  The  San  Antonio  Mountains  are  an  irregular  clump, 
south  of  the  Toquima  Range,  and  ai-e  separated  from  this  range  by 
a  gap  only  a  few  miles  wide.  Thej^  are  surrounded  on  all  sides  by 
detritus-covered  plains. 

TOPOGRAPHY. 

The  Toquima  Range  has  comparatively  great  relief.  In  general  it 
consists  of  a  single  ridge  of  moderate  breadth.  At  its  southern  end, 
near  the  town  of  Belmont,  this  splits  in  two,  the  main  ridge  trending : 
a  little  west  of  south  toward  the  San  Antonio  Mountains,  while  a  minor 
one  diverges  and  runs  in  a  southeasterly  direction  into  the  Monitor 
Range.  Between  the  two  ridges  is  a  low  valley,  filled  with  Pleistocene 
detritus. 

The  range  is  essentially  volcanic,  but  in  places  is  ex]30sed  a  core  of 
Paleozoic  rocks  beneath,  indicating  that  here,  as  in  the  Hot  Creek 
Range,  the  Antelope  Mountains,  and  others,  there  existed  a  distinct 
range  of  Paleozoic  rocks  before  the  lava  efi'usion,  which  has  now 
almost  completely  masked  the  stratified  rocks  and  given  the  range  the 
aspect  of  being  primaril}'  volcanic. 

SEDIMENTARY  ROCKS.     • 

The  range  was  crossed  by  the  writer  only  at  one  point.  His  route 
lay  from  the  town  of  Belmont,  around  the  southern  end  of  the  range, 
along  the  road  to  Cloverdale.  Along  this  route  no  stratified  rocks 
could  be  seen  in  the  range.  North  of  Belmont  all  is  apparently  vol- 
canic. This  impression  has  been  confirmed  by  reconnaissance  notes 
made  bj'^  Messrs.  Gilbert*  and  Emmons.^    Mr.  Emmons  suggests  that 

(I  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  II,  p.  566.  -     ' 

'>  U.  S.  Geol.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  121. 
cU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  Ill,  p.  393. 


SPURB.I  TOQUIMA    EANGE.  01 

the  core  of  the  range  some  distance  north  of  Belmont  may  be  com- 
posed of  stratified  rocks,  hut  the  first  point  where  they  have  been 
observed  is  just  east  of  Belmont,  where  occurs  a  series  of  black  limy 
slates  and  gray  finely  crystalline  limestone,  banded  black  and  white, 
and  often  siliceous.  The  formation  is  preeminently  a  slaty  one  and 
has  often  the  aspect  of  a  schist.  This  aspect  is  due  to  metamorpliisin, 
occasioned  by  certain  siliceous  dikes  of  the  granitic  family.  One 
great  dike  is  half  a  mile  wide  and  runs  in  a  north-south  direction. 
Near  its  junction  the  shaly  limestones  become  transformed  into  jas- 
peroid,  and  in  places  by  the  development  of  mica  the  rock  j)asses  into 
mica-schist.  Some  of  the  jasperoid  is  also  schistose,  and  contains 
small  bunches  of  red  and  j^ellow  metallic  oxides,  which  give  it  the 
asj)ect  of  a  knotted  schist. 

The  stratified  rocks  here  are  tilted  at  high  angles.  Where  observed 
by  the  writer  they  were  mostly  vertical,  but  Mr.  Emmons  found  a 
general  easterlj"  dip. 

In  the  slates  Mr.  Gilbert '^  found  graptolites,  which  referred  the 
rocks  to  the  Silurian  age.  According  to  Mr.  Walcott,'^  the  rocks  prob- 
ably correspond  to  a  i)art  of  the  nj)per  Pogonip  formation  of  Eureka. 
Mr.  Gilbert^  estimates  the  apparent  thickness  of  the  stratified  series 
at  Belmont  at  4,000  or  5,000  feet. 

On  the  road  leading  from  Belmont  southwest  toward  Cloverdale  the 
same  series  of  strata  is  found  at  the  eastern  base  of  the  main  ridge. 
The  chief  rock  is  compact  limy  black  slate,  often  metamorphic  and 
schistose,  corresponding  closelj^  with  the  rocks  just  east  of  Belmont. 
The  metamorphism  is  evidently,  as  in  the  former  case,  connected  uith 
intrusive  masses  of  granite  and  rhyolite.  By  these  the  slate  is  some- 
times transformed  into  an  unsheared  jasperoid  or  to  a  quartz-schist 
(the  latter  often  containing  actinolite  and  staurolite)  and  sometimes 
into  highly  crystalline  mica-schist.  A  mile  south  of  the  most  north- 
ern outcroj^  found  the  shales  are  overlain  bj^  about  200  feet  of  massive 
white  quartzite,  which  is  probably  the  Eureka  formation.  The  quartz- 
ites  and  underlying  beds  are  exposed  south  of  here  for  some  distance 
till  they  disappear  under  Pleistocene  detritus  on  one  side  and  volcanic 
rocks  on  the  other.  Farther  southwest,  however,  at  the  spring,  is  found 
another  small  patch  of  the  schistose  slates  capped  by  the  quartzite. 
This  patch  is  surrounded  on  all  sides  by  rhyolites,  and  is  chiefiy  altei-ed 
into  jasperoid  seamed  with  iron. 

Looking  eastward  from  the  eastern  base  of  the  main  ridge  a  portion 
of  the  minor  ridge  which  runs  southeasterly  from  Belmont  is  seen  to  be 
composed  of  stratified  rocks  similar  to  those  just  described.  Aj)par- 
ently  the  schists  and  the  overljang  white  quartzite  can  be  recognized. 

a  U.  S.  Geol.  Surv  W.  One  Hundredth  Mer.,  Vol.  Ill,  p  180. 
i-Mon.  U.  S.  Geol.  Survey  Vol.  Vm,  p.  2. 
"•■Op.  cit.,  p.  '.jH. 


92  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH   PARALLEL,    [bull. 

IGNEOUS  ROCKS. 


The  whole  northern  part  of  the  Toquima  Range  appears  to  be  cov- 
ered up  by  great  flows  of  rhyolite.  Just  east  of  Belmont  the  foothills 
bordering  the  area  of  stratified  rocks  are  composed  of  rhyolite  running 
out  to  the  north  toward  the  main  mass.  Rhyolite  is  also  found  in 
large  quantities  southwest  of  Belmont.  This  area  stretches  north 
and,  growing  broader,  joins  the  great  mass  whicli  covers  the  northern 
part  of  the  range.  To  the  south  also  it  appears  to  stretch  across  the 
gap  to  the  San  Antonio  Mountains.  Similai^ly,  the  rocks  of  the  minor 
ridge  which  runs  southeast  from  Belmont  are  mainly  rhyolitos,  form- 
ing a  continuous  body  with  the  rhyolites  of  the  Monitor  Range. 

DIKE  ROCKS. 

Near  Belmont  there  is  a  considerable  development  of  coarse-grained 
granitic  rocks.  In  several  cases  these  are  found  to  be  intrusive  into 
the  stratified  I'ocks.  A  mile  south  of  Belmont  is  an  exposure  of  coarse 
granite-porphyr}^  with  sparse  biotite  and  numerous  large  orthoclase 
phenocrysts  from  2  to  4  inches  long.  This  may  be  continuous  with 
the  great  dike  before  noted  as  running  north  and  south  just  east  of 
Belmont  and  having  a  width  of  half  a  mile. 

The  rocks  of  this  dike,  however,  are  different,  being  finer  grained 
and  in  general  more  siliceous.  They  consist  chieflj^  of  quartz  and 
feldspar.  In, some  places  the  rock  becomes  mostl}^  quartz;  in  others 
mainlj^  feldspar.  Quartz  veins  are  abundant,  irregular,  and  segrega- 
tional,  and  evidently  are  the  results  of  crystallization  contempora- 
neous in  a  general  way  with  the- crystallization  of  the  rest  of  the  rock. 
Biotite  is  often  sparsely  present,  and  in  some  x^laces  the  rock  contains 
considerable  muscovite  and  even  passes  into  muscovitic  quartz  veins. 
Thin  sections  of  the  rock  examined  show  in  one  case  a  fine-grained 
biotite-quartz-raonzonite;  in  another  case  siliceous  muscovite-biotite- 
granite,  peculiar  in  having  certain  areas  entirely  of  quartz.  This 
rock  is  evidently  closely  related  with  another  which  is  essentially 
composed  of  quartz  and  muscovite,  Avith  a  little  albite.  This  is  a 
variation  of  the  muscovite-biotite-granite,  in  which  muscovite  has 
largely  taken  the  place  of  feldspar.  The  distinction  between  this 
type  and  the  micaceous  quartz  veins  which  occur  in  close  connection 
with  it,  is  not  sharp  «. 

STRUCTURE. 

The  Silurian  shales  which  occur  just  east  of  Belmont  have  a  strike 
of  N.  35°  W.,  and  change  from  vertical  to  a  generally  easterly  dip. 
Southwest  of  Belmont,  on  the  eastern  side  of  the  main  ridge,  the  same 


a  J.  E.  Spurr,  Quartz-muscovite  rock  from  Belmont,  Nev.:  Am.  Jour.  Sci.,  4th  series,  Vol.  X, 
1900,  p.  351. 


SPURR]  TOYABE    RANGE.  93 

rocks  luive  a  general  uortli-soutli  strike  and  a  westerly  dip  of  20°. 
The  two  locations,  therefore,  may  be  on  the  two  limbs  of  an  anticli- 
nal fold.  The  fnrther  strnctni-e  of  the  stratified  rocivs  is  concealed 
beneath  the  lava  flows. 

ORES. 

In  the  vicinity  of  Belmont  there  has  been  considerable  ore  dei^osi- 
tion,  which  in  the  time  of  Nevada's  prosperity  made  the  region  one 
of  considerable  wealth.  At  present  the  mining  indnstry  is  perfectly 
dormant.  During  the  period  of  activity  the  region  was  described  by 
Mr.  Emmons."  According  to  him  the  ores  occur  generally  in  white 
quartz  veins,  often  several  feet  in  width,  and  consist  princij)ally  of 
stetefeldtite  (an  argentiferous  ore  of  antimony)  with  which  is  com- 
bined lead,  silver,  copper,  and  iron.  The  metallic  minerals  are  scat- 
tered through  the  quartz  in  bunches  or  disseminated  particles — rarely 
in  banded  form.  The  veins  are  found  cutting  the  Silurian  shales  and 
limestones,  and  frequent!}'  are  close  to  tlie  intrusive  granitic  dikes. 

It  appears  to  the  writer  that  there  is  a  genetic  connection  between 
the  intrusive  rocks  and  the  inetalliferous  quartz  veins  of  this  dis- 
trict. ^ 

TOYABE   RANGE. 

The  Toyabe  Range  lies  next  west  of  the  Toquima  and  extends  south- 
ward about  the  same  distance.  To  the  north,  however,  it  has  a  greater 
length,  running  along  the  western  border  of  the  desert  into  which  the 
Toquima  Range  merges  at  its  northern  end.  Thus  the  entire  length 
of  the  Toyabe  Range  is  about  100  miles.  It  lias  a  uniform  north - 
northeast  trend. 

That  portion  of  the  Toj^abe  Range  which  lies  north  of  Austin  has 
been  included  in  the  general  maps  of  the  Fortieth  Parallel  Survey. 
From  Austin  southward  nearly  to  the  southern  end  of  the  i^ange,  the 
mountains  have  been  made  the  subject  of  a  special  study  by  Mr. 
Emmons. '■  The  writer  observed  the  range  at  its  extreme  southern 
end,  and  also  its  western  base,  along  the  valley  which  separates  it 
from  the  closely  adjacent  Reese  River  Range. 

TOPOGRAPHY. 

The  topography  of  the  Toyabe  Range  is  marked  by  features  of  con- 
siderable contrast,  the  mountains  being  sharp  and  high  and  the  inter- 
vening canyons  deeply  cut.  Throughout  most  of  its  course  the  range 
consists  of  a  single  ridge  in  its  central  portion.  The  southern  ends  of 
this  range  and  of  the  Reese  River  Range  converge  until  they  almost 
unite. 

The  southern  part  of  the  range  is  essentially  volcanic;  while  the 
rest  is  composed  chiefly  of  granite  and  Paleozoic  strata.     The  erosion 

«U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  Ill,  p.  393. 

&  J.  E.  Spurr,  Am.  Jour.  Sci.,  4th  series,  Vol.  X,  1900,  p.  365. 

cQp.  cit.,  p.  320;  Atlas.  PI.  XIII. 


94  GEOLOGY    OF    NEVADA   SOUTH    OF    ■iOTH    PARALLEL,     [bull. 20; 

of  the  lavas  appears  to  have  been  quite  as  profound  as  that  of  the 
stratified  rocks,  showing  that  a  considerable  period  has  elapsed  since 
the  effusion  of  volcanic  material. 

In  the  valley  which  separates  the  southern  end  of  the  Toyabe  Range 
from  the  corresponding  portion  of  the  Reese  River  Range  there  is  a 
higli  divide,  separating  the  north-flowing  drainage  of  Reese  River 
from  that  which  flows  south  into  the  desert  plain  at  Cloverdale.  The 
south-flowing  drainage  runs  in  a  canyon  cut  into  the  bottom  of  the 
valley,  with  rhyolite  walls  which  go  up  at  angles  of  from  45°  to  65°  to 
heights  of  700  or  800  feet.  At  its  bottom  is  a  level  floor  covered  with 
wash  and  sagebrush,  and  in  the  center  of  this  floor  is  an  arroyo  5  or 
6  feet  deep.  At  Cloverdale  this  bottom  is  one-quarter  of  a  mile 
across,  while  7  or  8  miles  up  it  is  barely  30  yards.  The  stream  which 
flows  in  this  canyon  is  derived  from  a  spring.  This  case  is  like  one 
described  in  the  Snake  Range  region. 

Another  noteworthy  feature  of  the  erosion  of  this  range,  according 
to  Mr.  Emmons,  is  the  occurrence  of  basins  at  the  heads  of  some  of 
the  canyons,  which  basins,  he  infers,  were  formerly  occupied  by  glaciers. 
At  the  mouth  of  one  of  the  canyons  Mr.  Emmons  "•  found  glacial  strige, 
which  strengthened  his  belief.  On  most  of  the  Great  Basin  ranges,  as 
is  well  known,  there  are  no  marks  of  glaciation. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

All  the  stratified  Paleozoic  strata  of  the  Toyabe  Range  were  mapped 
by  the  Fortieth  Parallel  geologists  as  Carboniferous,  since  (^arbonif-  \ 
erous  fossils  were  the  only  ones  found  in  the  series.  These  occurred 
in  limestones.  Beneath  the  limestones  was  a  thick  series  of  slates, 
which  were  regarded  as  the  same  as  those  in  the  Toquima  Range  near 
Belmont.  The  subsequent  finding  by  Mr.  Gilbert  of  fossils  in  the 
Belmont  slates  determined  them  as  Silurian.  Beneath  these  slates, 
in  the  Toyabe  Range,  Mr.  Emmons  has  described  a  series  of  compact 
white  quartzites  with  some  thin  beds  of  white  gi-anular  limestone,  the 
series  being  several  thousand  feet  thick.  The  quartzites  underlie  the 
slate  series  in  apj)arent  conformity,  and  outcroi)  in  places  along  the 
eastern  face  of  the  south  half  of  the  range. 

Farther  north,  beyond  Austin,  the  high  mountain  called  the  Dome 
has  been  described  by  Mr.  Hague  ^  as  consisting  of  nearly  white 
quartzite  beds,  which  seem  to  be  bent  into  a  broad  anticlinal  fold. 
These  are  overlain  by  beds  of  siliceous  and  argillaceous  slates,  and 
these  by  compact  gray  limestones.  This  is  evidently  the  same  series 
as  described  by  Mr.  Emmons.  The  thickness  of  the  quartzites  is  not 
estimated,  but  must  be  great. 


a  U.  S.  aeol.  Expl.  Fortieth  Par.,  Vol.  Ill,  p.  328. 
bldem,  Vol.  II,  p.  630. 


SPURR.]  TOYABE    RANGE.  95 

No  fossils  were  found  in  tliese  quartzites,  but  in  the  Eureka  section 
no  such  quartzite  exist  except  that  of  the  basal  Cambrian;  and  the 
position  of  this  series  in  tlie  Toj^abe  Range  above  probable  Silurian 
slates  strengthens  the  belief  that  it  also  is  Cambrian. 

SILURIAN. 

As  before  noted,  Mr.  Emmons  has  described,  overlying  the  heavy 
quartzites,  an  estimated  thickness  of  7,000  feet  of  limestone  shales, 
with  siliceous  clay  slates,  locally  metamorphosed  into  schistose  rocks. 
Mr.  Emmons  regarded  these  slates  as  the  same  as  at  Belmont.  In 
these  latter  rocks  Silurian  fossils  have  since  been  found.  In  the 
Eureka  section  the  thickness  of  the  Silurian  is  estimated  at  5,000  feet. 

This  slate  series  occupies  the  central  portion  of  the  ranee,  the  gen- 
eral structure  being  anticlinal. 

DEVONIAN. 

Whether  or  not  the  Devonian  exists  in  tliis  range  is  not  certain. 
The  i3resence  of  Carboniferous  and  probable  Silurian  makes  it  seem 
veiy  possible  that  the  Devonian  also  conies  in,  although  it  has  not 
been"  recognized. 

CARBONIFEROUS. 

Overljdng  the  slate  series  which  has  just  been  referred  to  the 
Silurian,  Mr.  Emmons  "'  has  described  a  compact  dark-blue  limestone 
which  lies  conformably  upon  the  slates  and  is  exposed  on  both  flanks 
of  the  range  on  the  two  sides  of  the  general  anticlimil  fold  which  is 
the  chief  structural  feature.  In  this  limestone.  Mr.  Emmons  found 
Fusiilina  cylindrica  and  8yri7igopora. 

TERTIARY. 

Near  the  northern  end  of  the  range  Mr.  Hague ^  has  described, 
beneath  i-hyolite,  beds  of  volcanic  ash  which,  although  without  deter- 
minable fossils,  he  referred  to  the  Miocene.  These  beds  are  older  than 
the  rhyolite  and  have  been  disturbed,  since  their  deposition,  by  the 
intrusion  of  igneous  rocks,  so  that  they  underlie  unconformably  sup- 
posedly Pliocene  strata,  which  are  younger  than  the  rhyolite. 

IGNEOUS   ROCKS. 

A  considerable  portion  of  the  Toyabe  Range  is  made  up  of  granite 
and  volcanic  rocks. 


Mr.  Emmons^  has  described  five  bodies  of  granite,  all  intrusive  into 
Paleozoic  strata.  The  rocks  vary  somewhat  in  texture  and  composi- 
tion, but  are  generally  markedly  siliceous,  being  characterized  by  a 


aU.  S.  Geol.  Expl.  Fortieth  Par..  Vol.  Ill,  p  3^3.        6Idem,  YqI-,  II.  ?■  6^^        "^V-  cit.,  p.  324. 


96  GEOLOUr    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.308. 

large  ijroportiou  of  quartz,  an  almost  entire  absence  of  hornblende, 
and  a  small  j)roportion  of  mica.  Associated  with  the  granite  are  fine- 
grained dikes. 

RHYOLITE. 

Volcanic  rocks  occur  at  intervals  along  the  flanks  of  the  range,  but 
the  most  important  mass  is  at  the  southern  end,  where  for  30  miles  it 
completely  conceals  the  granite  and  the  stratified  rocks. 

Among  the  volcanic  rocks,  rhyolite  is  the  only  one  that  lias  any 
very  wide  distribution,  so  far  as  observed.  Mr.  Emmons  notes  tliat 
rhj^olite  occurs  in  exceptionally  large  masses  and  is  of  comparatively 
uniform  coarse  texture,  having  a  granitic  a^jpearance  in  tlie  hand 
specimen.  At  the  southern  end  of  the  range  the  present  writer  has 
studied  the  rhyolites,  which  are  here  associated  with  tuffs.  The  gen- 
eral type  is  biotite-hornblende-rhyolite,  similar  to  the  lava  which  forms 
the  southern  end  of  the  adjacent  Toquima  Range. 

AUGITE-BASALT. 

In  the  little  valley  which  separates  the  southern  end  of  the  Toyabe 
Range  from  the  Reese  River  Range  there  was  found,  near  the  head 
of  the  Reese  River  drainage,  a  small  area  of  augite-basalt. 

RELATIVE  AGE  OF  THE  IGNEOUS  ROCKS. 

As  in  the  Toquima  Range,  the  intrusive  granites  of  the  Toyabe 
Range  and  the  rhyolites  show  marked  consanguinity  in  composition.  ; 
Each  is  characterized  by  biotite  as  the  chief  ferromagnesian  mineral. 

The  augite-basalt  is  decidedly  younger  than  the  rhyolite,  since  it  ' 
was  poured  out  in  a  valley  which  has  been  deeply  cut  into  the  latter 
rock. 

STRUCTURE. 

According  to  Mr.  Emmons «  the  range  owes  its  existence  chiefly  to 
a  lateral  compression,  which  has  thrown  the  stratified  rocks  into 
north-south  anticlinal  and  synclinal  folds.  In  addition  to  this 
there  has  been  another  pressure,  coming  from  a  different  direction, 
which  has  distorted  and  dislocated  these  folds.  The  main  fold  of  the 
range  is  an  anticline,  which  occupies  the  whole  central  part  of  the 
range.  The  axis  of  this  fold  has  an  extreme  variation  from  northeast 
at  its  northern  end  to  northwest  at  its  southern.  South  of  here,  at 
Ophir  Canyon,  Mr.  Emmons  noted  a  syncline,  probably  adjacent  to 
the  main  anticline.  This  syncline,  however,  was  probably  formed  by 
the  intrusion  of  granite.  To  the  north  of  the  central  part  of  the 
range,  in  the  vicinity  of  Austin,  another  synclinal  fold  appears,  which 
also  seems  to  be  connected  with  a  granitic  intrusion.     Farther  north, 

aXJ-  S.  Geol.  Expl.  Fortietli  Par.,  Vol.  Ill,  p.  326. 


SPURR]  TOYABE    KANGE.  97 

as  stated,    the   striictiive  of    the   high   mountain   called,   the   Dome 
appeared  to  Mr.  Hague  "^  to  he  anticlinal. 

ORES. 

Formerly  the  ores  of  the  Toyabe  Range  were  of  great  economic 
importance,  but  with  the  decline  of  the  mining  industries  of  Nevada 
they  have  been  almost  forgotten.  The  principal  mining  region  was  in 
the  neighborhood  of  Austin,  but  mines  were  found  from  here  south- 
ward all  along  the  range.  Mr.  Emmons  has  described  many  of  the 
deposits,  which  in  nearly  ever}^  case  consist  of  veins  of  white  quartz 
carrying  metallic  sulphides  in  irregularly  disseminated  bunches  and 
streaks.  In  the  vicinity  of  Austin,  the  oldest  mining  district  in  the 
State,  the  veins  are  mostly  in  granite,  and  rich  ores  do  not  appear  to 
occur  in  other  rocks.  In  other  parts  of  the  range,  however,  the  veins 
occur  in  the  stratified  rocks.  Besides  quartz  as  gangue  mineral,  man- 
ganese spar  and  calc  spar  were  noted,  while  the  metallic  sulphides 
comprise  proustite,  pyrargyrite,  stephanite,  polybasite,  tetrahedrite, 
argentiferous  galena,  zinc  blende,  copper  pyrites,  and  iron  pyrites. 
In  some  of  the  veins  the  chief  silver-bearing  mineral  is  a  mixed  sul- 
phide of  antimony,  as  is  the  case  in  the  neighborhood  of  Belmont. 
The  veins  are  often  faulted. 

As  in  the  case  with  the  ores  at  Belmont,  there  is  probably  an  inti- 
mate connection  between  the  metalliferous  quartz  veins  and  the 
intrusive  rocks. 

aU.  S.  Geol.  Espl.  Fortieth  Par.,  Vol.  II,  p.  630. 

Bull.  2U8— U3 7 


CHAPTER    II. 
KAISTGES   OF  WEST-CKISTTRAL  ISTEVADA. 

REESE  RIVER  RANGE. 

The  Reese  River  Range  lies  next  west  of  the  Toyabe  Range,  from 
which  it  is  separated  only  by  a  narrow  north-south  valley  at  its 
southern  end.  From  here  it  extends  in  a  direction  a  little  east  of 
north  about  100  miles  into  the  area  of  the  Fortieth  Parallel  surveys. 
Farther  north  the  same  general  line  of  elevations  is  continued  in  the 
Shoshone  Range. 

TOPOGRAPHY. 

So  far  as' observed,  the  Reese  River  Range  is  composed  entirely  of 
igneous  rocks,  and  the  forms  produced  by  erosion  have  therefore  a 
certain  uniformit3^  The  summits  show  peaks  which  resemble  rem- 
nants of  ancient  volcanic  cones,  and  the  valleys  which  furrow  the 
flanks  are  deeply  cut. 

The  valley  which  sepai-ates  the  Reese  River  Range  from  the  Toyabe 
Range  at  its  southern  end  has  considerable  interest.  Its  broad 
rounded  form,  as  contrasted  with  the  sharp  incision  of  the  lesser 
mountain  valleys,  shows  that  it  has  not  been  jDroduced  since  the 
effusion  of  the  lavas,  but  existed  previously;  yet  the  bottom  of  the 
valley  consists  of  an  unknown  thickness  of  lava,  similar  to  that  of 
the  mountains  on  both  sides.  Subsequent  to  the  iDcriod  of  effusion, 
erosion  has  formed  deep  gorges  in  the  valley  bottom. 

Fifteen  miles  north  of  the  southern  end  of  the  Reese  River  Range 
there  is  in  the  valley  a  divide  which  separates  the  northward-flowing 
drainage  of  Reese  River  from  that  which  runs  south.  The  southward- 
flowing  drainage  is  in  a  canyon  which  is  cut  below  the  main  valley 
floor  700  or  800  feet.®  On  the  north  side  of  the  divide,  the  descent  is 
sharp  into  a  broad,  V-shaped  valley  cut  in  the  rhyolite.  Farther 
north,  where  the  mountains  diverge,  the  valley  suddenly  widens,  and 
at  the  same  time  the  topography  of  the  base  of  the  mountains  on  both 
sides  changes,  a  broad,  gently  sloping  plateau  taking  the  place  of  the 
irregular  hill  topography  of  the  higher  valley.  In  the  middle  of  this 
plateau  the  valley  in  which  the  uppermost  drainage  of  Reese  River 
flows  is  several  miles  wide. 

a  See  p.  9i. 
98' 


SPURK.]  REESE    EIVER    AND    ELLSWORTH   RANGES.  99 

IGNEOUS  ROCKS. 

So  far  as  seen,  the  range  is  composed  mainly  of  great  masses  of 
rlij^olite,  similar  to  the  lava  wliicli  makes  np  the  southern  end  of  the 
Toyabe  Range.  Along  the  eastern  base  of  the  mountains,  at  their 
southern  end,  are  abundant  dejjosits  of  white  volcanic  ash.  The  erup- 
tions whieli  poured  out  the  lava  must,  therefore,  have  been  of  an 
explosive  nature. 

In  the  valley  between  the  Keese  River  Range  and  the  Toyabe 
Range,  at  a  point  southeast  of  lone,  a  flow  of  augite-basalt  was  found. 
On  the  opposite  side  of  the  range,  in  the  vicinity  of  lone,  there  is  a 
considerable  body  of  the  same  rock. 

On  the  edge  of  the  desert  valley,  1  or  2  miles  west  from  lone,  there 
is  a  basic  lava  which  appears,  upon  microscopic  examination,  to  be 
biotite-andesite. 

The  low  ridges  running  south  from  Cloverdale  to  the  Monte  Cristo 
Mountains  are  mainly  flat  volcanic  mesas.  As  seen  from  tlie  vicinity 
of  lone,  the  Reese  River  Range  for  10  or  15  miles  north  is  evidently 
volcanic,  and  is  x)robably  mainly  so  up  to  the  junction  of  the  Fortieth 
Parallel  maj),  where  the  Shoshone  Range  is  represented  as  all  rhyolite. 

AGE   OF   LAVAS. 

The  augite-basalt  on  both  sides  of  the  range  is  plainly  younger  than 
the  rhyolite,  and  appears  to  lie  against  the  flanks  of  the  hills  eroded 
from  it. 

ELLSWORTH  RANGE. 

The  name  Ellsworth  Range  is  here  applied  to  the  extreme  southern 
end  of  a  series  of  rather  disconnected  ridges  which  farther  north  are 
known  as  the  Desatoya  Mountains.  This  southern  end,  so  named 
from  the  decayed  mining  camj)  of  Ellsworth,  is  narrow,  and  consists 
of  a  single  ridge  which  reaches  a  moderately  great  altitude. 

In  general  the  range  seems  to  be  composed  of  an  ancient  series  of 
volcanics  and  derived  tuffs,  Avith  limestones.  These  are  cut  by  dikes 
and  are  capped  and  often  entirely  hidden  by  late  volcanic  flows. 

SEDIMENTARY    ROCKS. 

The  range  was  crossed  by  the  writer  between  Ellsworth,  on  the  east 
side,  and  Downieville,  on  the  west.  On  the  road  some  miles  west  of 
Ellsworth  is  a  comparatively  small  outcrop  of  white  granular  lime- 
stone, consisting  of  loosely  cohering  calcite  crj^stals,  which  give  a 
granular  appearance  not  unlike  that  of  sandstone.  This  rock  is  asso- 
ciated with  an  altered  green  rock  of  probable  igneous  origin,  which 
is  cut  by  siliceous  dikes  and  is  frequently  mineralized.  The  only 
specimen  of  the  green  rock  examined  turned  out  to  be  made  up  of 
epidote,  quartz,  and  calcite,  all  probably  secondary  and  resultant 


100  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 308. 

from  alteratiou  accompauying  the  introduction  of  tlie  metallic  sul- 
phides which  are  frequently  found  disseminated  in  the  rock. 

On  the  summit  of  the  pass,  separated  from  the  locality  just  men- 
tioned by  a  sheet  of  overlying  basic  lava,  there  is  found,  immediately 
beneath  the  volcanic  rock,  a  dense  sandstone  or  tuff,  which  on  micro- 
scopic examination  is  found  to  consist  of  rounded  quartz  grains  and 
altered  feldsj^ar  fragments.  This  tuff  contains  occasionally  angular 
fragments  of  lava  and  also  doubtful  x^lant  remains. 

From  here  to  the  foot  of  the  comparatively  steep  scarp  which  occurs 
along  the  western  face  of  the  range,  there  is  a  vertical  distance  of 
nearly  2,000  feet.  The  section  shows  a  single  rock  series,  all  prob- 
ably of  igneous  origin.  The  rocks  are  reddish  or  greenish,  often 
trap  like  and  nearly  always  contain  abundant  angular  fragments  of 
lava,  giving"  the  ajDpearance  of  a  breccia.  Rock  having  the  appear- 
ance of  red  sandstone  is  common,  but  when  examined  under  the  micro- 
scope this  is  found  to  consist  chiefly  of  highly  altered  feldspar  frag- 
ments, with  some  calcite  and  epidote,  the  whole  being  stained  with 
iron  oxide.  It  is  probable,  therefore,  that  this  rock  is  also  a  volcanic 
tuff.  More  abundant  than  this  ajjparent  red  sandstone  is  a  dense, 
greenish-looking  rock,  which  microscopic  examination  shows  to  be 
probably  a  hornblende-biotite-syenite-porphyry.  Below  the  chief 
mass  of  this  igneous  rock  there  is  again  found  a  great  thickness  of 
f eldspathic  tuff,  which  is  highly  colored  in  the  hand  specimen.  Under 
the  microscope  the  tuft"  is  seen  to  be  made  up  of  rounded  and  broken 
fragments  of  feldspar  in  a  kaolinic  matrix,  the  whole  colored  by  iron 
oxide.  Below  this  again  there  is  found  white  volcanic  tuff,  resem- 
bling ash,  but  containing  some  rounded,  apparently  waterworn, 
grains. 

The  dij)  of  this  series  of  igneous  rocks  and  tuffs  seems  to  be  in  gen- 
eral to  the  west,  although  the  folding  on  a  small  scale  is  considerable. 

At  the  base  of  the  abrupt  mountain  scarp  is  found  a  moderately 
thin-bedded  siliceous  limestone,  without  fossils.  The  general  strike 
is  north  and  south,  and  the  dip  20°  to  30°  W.  This  rock  is  found 
continuously  to  the  end  of  the  foothills  at  Downieville,  where  dark- 
blue  limestone  alternates  with  beds  of  white  and  gray  granular 
limestone  or  marble. 

In  the  whole  series  exposed  in  the  Ellsworth  Range  no  fossils  were 
found,  except  in  the  limestone  just  east  of  Downieville,  where  they 
were  too  poorly  preserved  to  warrant  collection. 

The  marble  or  white  granular  limestone  at  Downieville  resembles 
that  described  on  the  east  side  of  the  mountain,  above  Ellsworth. 
In  both  places  there  is  a  north-south  strike.  The  dip  in  the  occur- 
rence near  Ellsworth  is  an  easterly  one  of  4°,  while  near  Downieville 
it  is  westerly,  averaging  20°  or  30°.  It  may  be,  therefore,  that  the 
two  occurrences  are  on  opposite  sides  of  an  anticlinal  fold.  If  this 
is  the  case,  then  the  thick  series  of  interstratified  igneous  rocks  and 


SPURR.]  ELLSWORTH    HAISTGE.  101 

tuffs  wliicli  constitutes  the  core  of  tlie  mountain  lies  beneath  the 
limestone  series.  The  volcanic  series  must  be  at  least  2,000  feet  thick, 
the  limestone  series  hardly  less. 

If  we  had  no  other  data  than  the  preceding  we  would  hardly  be  able 
even  to  suggest  the  age  of  the  rocks.  We  have,  however,  from  the 
researches  of  the  Fortieth  Parallel  geologists,  in  the  region  not  far 
north,  results  which  may  help  us  in  correlating.  In  this  same  range 
near  New  Pass  Peak,  about  60  miles  northeast,  are  Triassic  strata 
which  Mr.  Emmons  has  described  in  the  following  terms'' : 

The  lowest  exjiosiires  show  strata  of  a  greenish,  somewhat  cherty  qtiartzite. 
Above  these,  forming  the  summit  of  the  ridge,  is  a  breccia-like  conglomerate, 
made  np  of  greenish  and  purple  clierty  fragments,  with  a  red  cement,  overlaid 
by  a  thickness  of  abont  1,000  feet  of  qnartzite  and  conglomerate,  weathering 
with  a  peculiar  yellowish-brown  earthy  surface.  On  the  western  slopes,  imme- 
diately miderlying  the  limestones,  is  a  bed  of  purple,  argillaceons  roofing  slate. 
As  exposed  in  Ammonite  Canyon,  there  lies  conformably  above  this  a  thickness 
of  1.000  to  1,500  feet  of  dark  grayish-bine,  compact,  earthy  limestones  of  the 
Star  Peak  grotip,  which  lithologically  can  not  be  distingiiished  from  the  Car- 
boniferous limestones.  At  the  contact  of  the  limestones  with  the  qnartzites  is  a 
band  of  yellow  calcareous  shales. 

The  underlying  greenish  cherty  quartzite  and  breccia-like  con- 
glomerate with  red  cement,  described  by  Mr.  Emmons,  recalls  the 
central  mass  of  tuffs  and  volcanic  rocks  near  Ellsworth,  while  the 
overlying,  dark  grayish-blue  limestones  are  similar  to  those  near 
Downieville.  Immediatel}^  above  the  limestones  Mr.  Emmons  found 
abundant  Triassic  fossils  in  a  series  of  shales  which  were  not 
observed  in  the  Downieville  section 

The  lower  of  the  two  series  at  l^ew  Pass  Peak  has  been  correlated 
by  Mr.  King  with  the  Koiijar.o  formation,  and  the  underlying  lime- 
stone with  the  Star  Peak  formation,  both  formations  occurring  in 
the  Triassic  of  West  Humboldt  Range.  Concerning  the  Koipato  in 
the  West  Humboldt  Mountains,  Mr.  King  writes  that  at  the  base  it 
consists  of  a  vast  thickness  of  quartzitic  and  argillaceous  beds. 
These  purely  sedimentary  rocks  are  observed  to  i3ass  lateral^  into  a 
rock  which  in  hand  specimens  resembles  an  eruptive  rock. 

This  whole  series  contains  no  distinct  beds  of  limestone,  and  wherever  analyzed 
is  remarkably  free  from  carbonate  of  lime.  Its  lower  limit  is  nowhere  seen  and, 
owing  to  the  disappearance  of  the  strata  planes  nnder  extreme  metamoi-phism, 
there  is  no  possible  mode  of  arriving  at  its  total  thickness.  The  upper  limit, 
however,  is  sharply  marked  by  an  abrupt  transition  from  the  schists  into  a  body 
of  dark  carbonaceous  limestone.  To  this  whole  underlying  group  of  schists  and 
porphyroids  we  have  given  the  title  Koipato.  from  the  Indian  name  of  this  range.'' 

Allowing  for  some  slight  difference  in  interpretation,  Mr.  King's 
characterization  of  the  Koii)ato  formation  applies  to  the  rocks  on  the 
western  face  of  the  range  between  Ellsworth  and  Downieville.  Mr. 
King  believed  that   the    transition    from    sedimentary   argillites    to 

«  U.  S.  Geol.  Expl.  Fortieth  Par. ,  Vol.  II.  p.  644. 
6  Idem,  Vol.  I,  p.  2H9. 


102  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

igneous  rocks  resulted  from  metamorphism,  while  in  the  case  of  the 
rocks  near  Ellsworth  those  which  possess  igneous  structure  are  almost 
without  doiTbt  ancient  volcanics,  which  pass  above  and  below,  and 
probably  laterally,  into  shales,  conglomerates,  and  water-laid  brec- 
cias derived  from  these  or  similar  igneous  rocks.  The  whole  series 
therefore  is  conceived  to  represent  the  products  of  a  period  of  ancient 
volcanic  activity. 

The  series  is  more  indurated,  altered,  and  oxidized  than  any  of  the 
Tertiary  volcanic  series,  and  no  similar  rocks 'are  known  in  the  Paleo- 
zoic of  Nevada.  Their  correlation  with  the  established  Triassic  for- 
mations is  therefore  j)lausible. 

IGNEOUS   ROCKS. 

The  oldest  igneous  rocks  of  the  range  are  those  just  described  as 
interstratified  with  the  tuffs  of  the  great  ancient  volcanic  series.  The 
only  specimen  examined  is  probably  a  hornblende-biotite-sj^enite- 
porphyry. 

Next  younger  than  these  ancient. volcanics  come  siliceous  dikes, 
which  are  well  exposed  on  the  eastern  face  of  the -range,  near  Ells- 
worth. The  most  easterly  outcrop  encountered  is  an  alaskite-por- 
phyrjT^  "■  containing  feldspar  phenocrysts  which  are  sometimes  as  much 
as  4  or  6  inches  long.  This  resembles  the  granitic  rock  described 
south  of  Belmont.  It  is  cut  b}^  several  narrow  dikes  of  liner-grained 
rock  having  the  same  composition,  but  not  porphja'itic.  These  silice- 
ous dikes  are  intrusive  into  metamorphosed  green  rock  just  west  of 
Ellsworth,  the  siliceous  rock  cutting  the  other  in  numerous  dikes. 

Covering  the  ancient  volcanic  rocks  and  the  later  alaskite  dikes 
there  is  found,  occupying  the  center  of  the  mountain  between  Ells- 
worth and  Downieville,  a  bed  of  volcanic  ash.  Above  this,  forming 
the  crest  of  the  range  and  constituting  all  the  high  peaks,  is  a  mas- 
sive, columnar-jointed  volcanic  rock.  A  specimen  of  this  proved  on 
examination  to  be  hyperstheue-aleutite.^  In  the  western  foothills, 
near  Downieville,  is  also  probably  a  patch  of  similar,  comj)aratively 
young  volcanic  rock,  and  north  of  Downieville  the  low  limestone 
mountains  are  succeeded  after  a  few  miles  by  a  chain  of  lower  hills, 
which  are,  in  part  at  least,  volcanic.  These  extend  northward  at  least 
10  or  15  miles.  At  the  southern  end  of  the  Desatoya  Range,  as  mapijed 
by  the  Fortieth  Parallel  geologists,  the  rocks  are  all  volcanic,  envelop- 
ing the  Triassic  strata  exposed  in  the  region  of  New  Pass  Peak. 

STRUCTURE. 

Apparentlj^  the  main  structure  of  the  range  is  anticlinal,  the 
ancient  volcanic  series  constituting  the  core,  from  which  the  overly- 

a  Alaskite  is  a  general  name  proposed  for  rocks  consisting  essentially  of  quartz  and  alkali  feld- 
spar, without  essential  ferromagnesian  minerals.  J.  E.  Spurr,  Classification  of  igneous  rocks 
according  to  composition:  Am.  Geol.  Vol.  XXV,  1000,  No.  3. 

6Aleutite  is  the  name  proposed  for  a  rock  intermediate  between  andesite  and  basalt.  J.  E. 
Spurr,  Classification  of  igneovis  rocks  according  to  composition:  Am.  Geol.,  Vol.  XXV,  1900,  No.  3. 


8PURR.]  PILOT   MOUNTAINS.  103 

ing  limestones  dip  away  on  both  sides.  Tnst  north  of  Downieville  the 
low  limestone  monntaius  are  separated  from  the  main  range  by  a  shal- 
low and  relatively  broad  valley.  The  structure  of  these  low  mountains 
is  anticlinal,  and  between  this  anticline  and  the  one  comprised  in  the 
main  ridge  is  a  syncline,  in  which  the  intervening  vallej^  lies. 

ORES. 

On  both  sides  of  the  range  there  are  ore  deposits,  once  of  great 
economic  value,  now  largely  abandoned.  The  mines  near  Ellsworth 
seem  to  be  in  the  ancient  igneous  formation,  and  these  old  rocks  show 
on  exposed  surfaces  carbonate  of  copper  and  on  fi-esh  breaks  copper 
pyi-ite.  Between  Downieville  and  the  top  of  the  mountains  also  there 
are  ore  deposits  in  the  ancient  volcanic  series.  At  Downieville  ores 
are  found  in  the  limestone,  resulting  apparently  from  replacement 
of  the  rock  by  sulphides. 

PILOT   MOUNTAINS. 

East  of  the  Excelsior  Range,  on  the  other  side  of  Soda  Springs  Val- 
ley, lies  a  short  but  comiaaratively  rugged  mountain  range  which  has 
a  north-south  trend,  changing  to  northwest  in  its  northern  portion. 
On  the  south  the  foothills  of  this  range  merge  into  those  of  the  Oan- 
delaria  Mountains,  and  are  separated  from  the  northern  end  of  the 
Monte  Cristo  Mountains  only  by  a  narrow  gai3.  On  the  north,  the 
Pilot  Mountains  pass  into  the  volcanic  hills  of  the  Galibs  Valley 
Range. 

The  highest  portion  of  the  range  is  Pilot  Mountain,  which  lies  just 
east  of  Sodaville.  On  the  west  face  of  this  mountain  there  is  a  bold 
scarp  (very  likely  a  simple  fault  scarp),  which  rises  from  a  point  which 
has  an  estimated  elevation  of  about  6,000  feet  above  sea  level.  Below 
this  point  there  are  immense  gulch  dumps,  or  alluvial  fans,  covering 
the  other  valley  detritus,  and  reaching  several  miles  westward  toward 
the  center  of  the  valley. 

SEDIMENTARY   ROCKS.       ' 
EARLY   TERTIARY   OR  MESOZOIC   SERIES. 

Most  of  Pilot  Mountain  is  made  up  of  stratified  rocks.  At  the  base 
is  a  series  of  gray  rocks  which,  on  account  of  a  slight  east-west  flex- 
ure, transverse  to  the  general  north-south  line  of  folding,  passes  down 
to  the  north  and  south  so  as  to  be  covered  by  the  valley  detritus. 
These  rocks  are  hard  to  identify  in  the  field  on  account  of  their  altered 
character,  but  microscopic  study  shows  them  to  consist  mainly  of  vol- 
canic tuffs,  generally  coarse,  sometimes  fine  and  slaty.  They  grade 
into  solid  lavas.  A  specimen  of  one  of  the  lava  sheets  on  examina- 
tion seems  to  be  andesite.  In  the  field  no  sharp  line  can  be  drawn 
between  the  tuffs  and  the  slaty  lavas.  These  rocks  are  cut  by  many 
dikes  of  siliceous  granite. 


104  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL.     [bull.2C(8. 

Overlying  tliis  gray  tnffaceous  series  are  reddish  sandstones,  shales, 
and  conglomerates,  which  in  tnrn  are  overlain  by  a  considerable 
thickness  of  purer  red  sandstone  and  quartzite,  which  forms  the  sum- 
mit of  the  mountains.  An  estimation  of  the  thickness  of  the  different 
rock  series  in  this  section  gives  1,000  feet  for  the  basal  tnffaceous 
series,  1,000  feet  for  the  sandstone,  shale,  and  conglomerate  series,  and 
also  1,000  feet  for  the  purer  red  sandstone  series,  making  a  total  of 
2,000  feet  of  red  sandstone,  shale,  and  conglomerate  overlying  1,000 
feet  of  the  gray  tufifaceous  series. 

Where  the  rocks  immediately  overlying  the  basal  grsty  series  were 
examined  at  the  base  of  the  mountain  they  were  found  to  be  red  or 
white  sandstone  and  quartzite,  sometimes  fine  and  calcareous,  some- 
times coarse  and  gritty.  There  is  also  much  red  sandstone  con- 
glomerate, indurated  and  squeezed.  The  pebbles  of  the  conglomerate 
seem  to  be  entirelj^  of  quartzite  and  chert.  This  reddish  sandstone 
and  shale  series  aj^pears  to  extend  northward  several  miles,  until 
overlain  by  later  volcanic  rocks.  On  the  south  it  does  not  extend  so 
far,  being  overlain  in  the  foothills  of  the  Pilot  Range  along  the  road 
between  Sodaville  and  Columbus  by  later  liorizontally  stratified 
sediments. 

The  upper  2,000  feet  of  red  sandstone,  shale,  and  conglomerate  is 
perhaps  the  same  series  as  that  described  as  occurring  in  tlie  Excel- 
sior Mountains,  just  across  the  valley  to  the  west.  The  underlain g 
gray  tnffaceous  series  is  not  found  in  the  Excelsior  Mountains.  Litho- 
logically,  some  of  the  tuffs  correspond  to  andesitic  tuffs  found  in  the 
folded  Earlier  Tertiary  series  of  the  Monte  Cristo  Mountains,  20  miles 
south  of  Pilot  Peak.  At  the  same  time,  the  series  has  a  verj^  strong 
lithologic  resemblance  to  the  supposedly  Triassic  beds  of  the  Ells- 
worth Range,  into  which  the  Pilot  Mountains  are  almost  directlj^  con- 
tinuous on  the  north. 

Mr.  H.  W.  Turner  has  recently  reported  Jurassic  limestone  and  slate 
in  the  Pilot  Mountains.  "  In  a  personal  letter  to  the  writer,  Mr.  Tur- 
ner states  that  at  the  north  base  of  the  mountains  he  found  abundant 
fossils  in  limestone,  which  Avere  examined  by  Prof.  J.  P.  Smith,  of 
Stanford  University,  who  pronounced  them  certainly  Jurassic. 

PLIOCENE. 

On  the  southern  side  of  Soda  Springs  Valley,  horizontally  stratified 
rolled  gravels  were  found  at  an  elevation  of  about  5,250  feet,  and 
were  referred  to  the  Pliocene  sediments  of  Shoshone  Lake.  Similar 
sediments  undoubtedly  exist  at  the  base  of  Pilot  Mountain,  but  they 
have  been  covered  ujp  by  the  enormous  subsequent  Pleistocene  gulch 
dumps,  which  form  a  belt  along  the  foot  of  the  mountain.  The  material 
in  these  dumps  manifestly  represents  the  larger  portion  of  that 
removed  from  the  gulches  which  cut  back  into  the  scarp  of  the  inoun- 

oGeol.  Soc.  Am.,  Berkeley,  Cal.,  Dec,  1900.    Report  in  Am.  Geologist,  Feb.,  1901,  p.  133. 


spuRR]  PILOT    AND    MONTE    CRISTO    MOUNTAINS.  105 

tain  above.     The    erosion    of    these    g'lilches    is,    therefore,    mainly 
Pleistocene. 

At  the  southern  end  of  the  Pilot  Mountains,  along  the  road  between 
Sodaville  and  Columbus,  is  a  considerable  area  of  horizontally  strati- 
fied fine  silts  and  hardened  clays,  with  some  volcanic  ash  beds.  This 
formation  constitutes  the  divide  between  Soda  Springs  Valley  and 
Columbus  Valley,  and  reaches  as  high  an  elevation  as  6,000  feet,  where 
it  is  overlain  by  a  sheet  of  basalt.  These  beds  are  evidently  the  result 
of  deposition  in  a  still  bodj^  of  water,  and  are  correlated  with  the  sim- 
ilar Pliocene  beds  described  elsewhere  in  this  region. 

IGNEOUS   ROCKS. 

PLEISTOCENE   OLIVINE-BASALT. 

At  the  southern  end  of  the  range,  overlying  probable  Pliocene  sedi- 
ments, occurs  a  thin-bedded,  dark,  vesicular  lava,  which  proves  to  be 
olivine-basalt.  From  its  occurrence  there  is  no  doubt  that  this  rock 
should  be  classified  with  the  other  Pleistocene  basalts  of  the  region. 

GRANITIC  ROCKS. 

Pilot  Mountain  contains  many  branching  dikes  and  irregular  masses 
of  intrusive  granitic  rock,  similar  to  that  across  the  vallej^  in  the 
eastern  end  of  the  Excelsior  Range.  A  typical  specimen,  examined 
microscopicallj',  proves  to  be  a  biotite-granite.  The  intrusives  seem 
to  be  chiefly  confined  to  the  base  of  the  mountain,  and  not  to  have 
reached,  in  veiy  great  quantity,  the  uppermost  strata.  The  granite 
is  accompanied  hj  alaskite,^'  and  in  the  vicinity  of  these  intrusions 
are  ore  deposits,  as  in  the  case  of  the  east  end  of  the  Excelsior  Moun- 
tains; and  the  ore  has  probably  had  a  genetic  connection  with  the 
igneous  rock. 

MONTE  CRISTO  MOUNTAINS. 

The  Monte  Cristo  Mountains  are  comparatively  short  and  low. 
The}"  have  a  general  north-south  trend,  and  extend  from  the  Pilot 
Mountains  on  the  north  to  the  Silver  Peak  Range  on  the  south,  with 
a  total  length  of  about  30  miles. 

SEDIMENTARY   ROCKS. 

On  the  road  between  Columbus  and  Silver  Peak  there  is  a  com- 
parativelj'  low  gap  in  the  Monte  Cristo  Range.  In  this  gap  are 
found  low  hills  of  white  shale  capped  by  a  porous  bed  which,  examined 
microscopically,  proved  to  be  a  calcareous  andesite  tufi".  From  this 
rock  a  collection  of  poorly  preserved  fossil  shells  was  made,  which 
Dr.  W.  H.  Dall  was  not  able  to  identify  with  cei-tainty.  Dr.  Dall 
thought  the   forms   suggested   a   fresh-water  origin.      He   found   a 

a  Rock  consisting  essentially  of  quartz  and  alkali  feldspar,  without  essential  ferromagnesian 
minerals. 


106  GEOLOGY    OP    NEVADA   SOUTH    OF   40TH   PARALLEL,     [bull.208. 

bivalve,  which  may  be  a  Sphcerium,  and  a  gasteropod  that  may  be  a 
Planorhis.  The  shales  contain  frequent  leaves  and  occasional  coal 
seams. 

These  sediments  are  capped  by  volcanic  rocks.  In  the  low  pass 
above  referred  to  the  immediately  overlying  rock  is  a  light-gray 
tordrillite.  "     Above  this  comes  andesite. 

At  the  northern  end  of  the  Monte  Cristo  Range  there  appears  to  be 
a  patch  of  stratified  rocks  similar  to  those  just  described,  the  inter- 
vening space  being  completelj^  covered  by  lavas. 

This  series  has  been  examined  somewhat  carefully  by  Mr.  H.  W. 
Turner,  who  has  named  it  the  Esmeralda  formation.  He  finds  that 
it  is  shown  at  various  points  in  the  Silver  Peak  Range,  and  that  it 
comprises  a  considerable  variety  of  sediments.*  According  to  him 
the  series  exposed  aggregates  at  least  2,000  feet,  and  is  composed 
chiefly  of  sandstone,  with  some  shale.  The  top  is  made  u]3  of  laeus- 
tral  marls  and  white  shales.  Mr.  Turner  collected  from  these  rocks 
fossil  shells,  fish  bones  and  scales,  and  dicotyledonous  leaves,  which 
were  examined  by  Dr.  J.  C.  Merriam,  Prof.  F.  A.  Lucas,  and  Dr.  F.  H. 
Knowlton.  Dr.  Merriam  lound  that  the  fossil  shells  indicate  an  early 
Miocene  or  a  late  Eocene  age  for  the  beds,  and  Dr.  Knowlton  found 
that  the  plant  remains  indicate  a  Middle  Tertiary  age.  The  fish 
remains,  so  far  as  yet  studied,  do  not  seem  determinate. 

The  Avriter  has  observed  in  the  region  south  of  liere,  notablj^  in  the 
neighborhood  of  Death  Vallej^  and  in  the  Mojave  Desert,  upturned 
Tertiary  sediments  which  he  is  inclined  to  correlate  with  the  beds  of 
the  Esmeralda  formation  in  the  Silver  Peak  and  Monte  Cristo 
Mountains. 

IGNEOUS   ROCKS. 

The  greater  portion  of  the  Monte  Cristo  Mountains  is  covered  by 
volcanic  rocks.  In  general,  dark  basic  lava  seeuis  to  overlie  lighter- 
colored  siliceous  lava. 

DESERT   MOUNTAINS. 

The  Desert  Mountains  form  an  irregular  group  which  runs  from 
the  southern  end  of  Mason  Valley  southeastward  to  near  the  north- 
western end  of  the  Gabbs  Yallej^  Range  at  the  northern  end  of  Walker 
Lake.  In  general  these  mountains  have  slight  relief,  although  north 
of  Mason  Valley  the  peaks  reach  a  considerable  height.  At  the 
southern  end  the  mountains  change  into  low  mesas  of  brilliant  color. 

These  mountains  are  composed  entirely  of  well-bedded  volcanic 
rocks.  At  the  extreme  northwestern  end  specimens  examined  prove 
to  be  biotite-hypersthene-andesite.     Along  the  southeastern  end,  near 

"Tordrillite  differs  from  a  rhyolite  in  being  more  siliceous  and  containing  no  essential  dark 
minerals.    J.E.  Spurr,  Am.Geol.,  Vol.  XXV,  19(10,  No.  3.  p.  230. 
bThe  Esmeralda  formation:  Am.  Geol.,  Vol.  XXV,  1900,  p.  168. 


sptTRR.]  GABBS    VALLEY    AND    GABBS    VALLEY    EANGE.  107 

the  liead  of  Walker  Lake,  the  old  beaches  of  tlie  Pleistocene  Lake 
Lahontan  inay  he  traced. 

GABBS  VALLEY  AND  GABBS  VALLEY  RANGE. 

Gabbs  Valley  is  a  broad,  flat-bottomed  basin,  almost  comi^letely  sur- 
rounded by  irregularly  distributed  volcanic  mountains.  The  higher 
mountains  to  the  south  of  the  vallej^  constitute  the  Gabbs  Valley 
Range,  which  extends  from  AValker  Lake  southeastward  for  about  40 
miles  to  the  Pilot  Mountains.  The  topography  of  this  range,  as  well 
as  of  the  hills  on  the  north  side  of  the  valley,  is  comparatively  primi- 
tlA^e,  the  valleys  being  regular  and  in  general  not  vei-y  deepl}'  cut, 
recalling  the  erosion  topography  of  the  sui3posedly  I'liocene  lake 
deposits  of  Pleasant  Valley  in  the  Snake  Range. 

SEDIMENTARY    ROCKS. 
EARLIER   TERTIARY   MARLS. 

Near  the  center  of  the  valley,  just  east  of  the  low  mountain  spur 
which  crosses  it,  and  on  the  Reese  River  road,  there  are  low  ridges  of 
gi-ay,  stratified  marl  containing  leaf  remains,  alternating  with  gravels 
and  more  solid  conglomerates.  Some  of  the  conglomerate  contains 
comparatively  alnindant  silicified  wood.  The  conglomerate,  when 
examined  microscopically,  proves  to  be  volcanic.  The  pebbles  are 
made  up  in  part  at  least  of  spherulitic  glass.  Some  pebbles  contain 
plienocrj^sts  of  feldspar,  of  species  indicating  that  the  lava  is  ande- 
sitic,  in  a  glassy  matrix  containing  broken  feldspar  and  biotite. 
Some  of  the  shaly  beds  associated  with  the  conglomerate  are  felds- 
pathic  tuff,  made  up  of  fine  fibrous  material,  with  larger  In-oken  frag- 
ments of  feldsi^ar  and  some  shreds  of  l)iotite.  These  beds  strike  north 
and  south  and  dip  about  8°  E. 

No  fossils  were  obtained  from  these  beds.  The  locality  is,  how- 
ever, at  a  higher  altitude  than  that  of  tlie  Pleistocene  lake  which, 
according  to  Professor  Russell,'^'  covered  tlie  lowest  part  of  the  valley 
just  west  of  here.  Also,  the  beds  seem  to  show  a  general  tilting,  and 
since,  according  to  Mr.  King,''''  the  last  marked  folding  in  this  area  was 
j)ost-Mlocene,  these  beds  are  verj'-  iikelj^  pre-Pliocene.  They  liave  the 
aspect  of  lacustrine  marls.  Lithologically,  they  coincide  with  the 
descriptions  given  by  Mr.  King  of  his  typical  Truckee  Miocene,  which 
consists  of  sandstones,  conglomerates,  and  tuffs  at  the  base,  witli  an 
enormous  thickness  of  volcanic  tuffs  at  the  top,  the  whole  series 
being  as  much  as  2,000  or  3,000  feet  thick.  The  typical  Miocene 
localities  of  King  are  situated  near  here  to  the  north.  Therefore  the 
beds  under  consideration  are  provisionally^  correlated  with  those 
described  b}^  Mr.  King.  They  have  also  a  general  resemblance  in 
their  nature,  derivation,  degree  of  induration,  and  especially  in  their 

a  Mon.  U.  S.  Geol.  Survey  Vol.  XI,  PL  XLVI.    b  XJ.  S.  GeoL  Expl.  Fortieth  Par.,  Vol.  I,  p.  4.55. 


108  G.EOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

containing  silicified  wood,  with  the  early  Tertiary  series  of  the  Silver 
Peak  region,  closelj^  adjacent  to  the  south.     (See  p.  185.) 

PLEISTOCENE. 

In  the  lowest  portion  of  Gabbs  Valley,  west  of  the  Tertiary  marls 
just  described,  is  a  broad  alkali  flat  or  playa,  covered  with  smooth, 
hard  mud.  This  was  perhaps  the  bottom  of  a  lake  inclosed  in  the 
Gabbs  Valley  Basin.  As  mapped  by  Professor  Russell,  it  was  contem- 
poraneous with  the  great  Lake  Lahontan,  but  separated  from  it. 

At  the  base  of  the  volcanic  mountains  there  is  a  continuous  apron 
of  detrital  material  sloping  away  at  an  angle  of  about  3|°  for  a  mile 
or  two  toward  the  middle  of  the  basin.  As  in  the  case  of  the  similar 
alluvial  deposits  investigated  hj  Mr.  Russell,^'  these  aprons  seem  to 
be  older  than  the  great  Pleistocene  lakes. 

The  effect  of  eolian  action,  of  importance  everywhere  in  the  Great 
Basin,  is  very  conspicuous  in  certain  portions  of  Gabbs  Valley. 
The  Avind-blown  sands  have  in  many  places  accumulated  in  consider- 
able mass. 

IGNEOUS   ROCKS. 

Most  of  the  mountains  surrounding  Gabbs  Valley,  including  the 
Gabbs  Valley  Range,  are  volcanic.  These  rocks  represent  a  variety 
of  species. 

Just  east  of  the  hot  spring  in  the  valley  the  road  passes  through  a 
gap  in  the  mountains  about  1,500  feet  deep,  the  sides  of  which  rise  at 
an  angle  of  about  50°.  The  rock  at  this  j)oint  varies  from  moderately 
fine  to  moderately  coarse,  but  it  is,  nevertheless,  always  holocrj^stal- 
line.  It  is  massive  and  verticall}^  jointed,  yet  has  a  distinct  horizon- 
tal bedding,  and  a  little  northeast  of  here  it  seems  to  be  underlain  by 
ash.  It  is  therefore  probably  effusive.  A  single  specimen  of  this 
rock,  examined  microscopically,  proves  to  be  a  hornblende-biotite- 
quartz-monzonite. 

On  the  mountain  ridge  which  separates  Gabbs  Valley  from  Walker 
Lake  Valley  the  lavas  which  dip  eastward  into  the  former  basin  at 
angles  of  10°  or  more,  in  color  gray  or  oxidized  bright  red,  prove  to 
be  biotite-,  hypersthene-,  and  hornblende-aleutites  and  andesites.  On 
all  the  mountains  to  the  north  of  here,  which  were  not  visited,  there 
appears  to  be  a  basal  light-gray  or  red  lava,  which  forms  the  highest 
peaks,  underlying  a  dark-brown  or  black  lava  which  forms  the  fringes 
of  the  mountains  and  sometimes  constitutes  a  cone  3^et  only  slight]}^ 
defaced. 

Where  tlie  road  crosses  the  extreme  western  end  of  the  Gabbs  Val- 
ley Range,  overlooking  Walker  Lake,  the  lavas  are  mixed  and  the 
hills  variegated,  the  colors  being  bright  red,  yellow,  gray,  greenish 

"  Mon.  U.  S.  Geol.  Survey  Vol.  XI,  p.  25G. 


SPURR.J 


EXCELSIOR    RANGE.  109 


yellow,  white,  and  black.  In  geueral  a  liglit-gray  lava  is  overlain  by 
dense  black  flows.  The  former  jiroved  to  be  biotite-andesite,  while 
the  latter  is  augite-basalt.  A  little  farther,  biotite-rhyolite  was  found, 
api^arently  underlying  the  basalt. 

EXCELSIOR  RANGE. 

The  name  Excelsior  Range  is  aj^plied  to  a  short,  rather  irregular 
group  of  mountains  which  lies  south  of  Walker  Lake,  and,  unlike  the 
most  of  the  ranges  of  this  region,  runs  in  a  general  east-Avest  direction, 
cutting  off  the  southern  end  of  Walker  Lake  Valley  and  extending 
from  the  southern  end  of  the  Walker  River  Range  eastward  to  Soda 
Springs  Valley.  The  entire  length  of  the  range  is  only  about  30  miles. 
The  main  range  has  to  the  north  of  it  several  high  spurs  which  run 
off  at  right  angles  and  connect  with  a  lower  east-west  ridge  parallel 
to  the  main  one,  farther  north.  To  the  south  also  a  number  of  north- 
south  spurs  connect  the  Excelsior  Mountains  with  the  Candelaria 
Mountains.  The  main  range  is  terminated  on  the  east  by  a  bold 
scarp  overlooking  Soda  Springs  Valley,  corresponding  to  the  west- 
facing  scarp  of  the  Pilot  Mountains  on  the  other  side. 

These  mountains  Avere  crossed  by  the  writer  on  the  road  between 
Hawthorne  and  Sodaville,  which  leads  through  Excelsior  Flat. 

SEDIMENTARY   ROCKS. 
LIMESTONE   SERIES    (EARLY   TERTIARY?). 

If  one  travels  along  the  above-mentioned  road  from  Walker  River 
Valley  eastward,  he  finds,  after  passing  through  a  belt  of  lava  which 
constitutes  the  foothills,  an  area  of  thin-bedded,  shaly,  sometimes 
compact,  blue  limestone.  This  limestone  is  overlain  by  a  lava  sheet, 
and  near  the  contact  is  baked  and  silicified  to  a  greenish  or  brown 
jasperoid  containing  segregated  nodules  of  silica.  The  stratification 
is  nearly  horizontal,  but  shows  local  contortion  and  horizontal  fault- 
ing, suggested  breaking  and  shoving  by  the  overriding  lava  sheet. 

Near  the  contact,  partly  in  the  blue  shaly  limestone,  partly  in  the 
same  rock  transformed  into  jasperoid  by  the  contact  metamorphism, 
were  found  fossils.  Mr.  T.  W.  Stanton,  of  the  National  Museum, 
reports  on  these  as  follows: 

Fossil  lot  No.  46,  from  the  Excelsior  Range,  road  between  Hawthorne  and 
Sodaville,  evidently  represents  two  distinct  beds,  one  a  hard  brown  siliceo-argilla- 
ceous  rock  and  the  other  a  dark-blue  limestone.  The  former  contains  several 
specimens  of  a  Corbula,  another  undetermined  bivalve,  and  a  very  imperfect 
Gasteropod  that  may  be  a  Natica  or  a  Vivapar us,,  th.Q  generic  character  not  pre- 
served.  These  are  probably  not  earlier  than  Cretaceous,  and  they  may  be  Tertiary. 

The  blue  limestone  fragments  yielded  a  small  Neritina,  a  Hydrohia  (?) ,  an 
Astarte  (?) ,  and  several  imperfect  specimens  of  two  or  three  other  small  bivalves. 
These  fossils  have  a  Tertiary  aspect.    They  are  certainly  not  older  than  Cretaceous. 


110  GEOI-OaY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.308. 

In  answer  to  a  query  as  to  tlie  conditions  of  deposition  indicated  by 
the  fossils  Mr.  Stanton  writes : 

The  fossils  in  lot  46  are  either  marine  or  brackish-water  form,  not  fresh  water. 
If  I  could  be  sure  that  the  bivalve  I  have  called  Astarte  (?)  really  belonged  to  that 
genus  there  would  be  no  doubt  that  they  are  marine.  The  other  genera  recog- 
nized live  in  both  salt  and  brackish  water. 

To  the  east  tliis  limestone  forms  a  well-defined  anticline,  with  a 
north-south  axis,  and  with  dips  of  20°  to  30°  on  both  sides.  Still 
farther  east  the  limestone  is  again  overlain  by  the  volcanic  rock 
wdiich  encircles  this  area. 

In  the  bottom  of  Excelsior  Flat,  near  its  eastern  side,  probablj^  the 
same  limestone  series  is  found,  but  more  altered  and  crushed  and 
veined  by  dynamic  action.  Badly  i^reserved  fossils  were  collected 
from  this  rock,  but  could  not  be  identified. 

The  thickness  of  this  limestone  series  was  roughly  estimated  at 
2,000  feet. 

SANDSTONE-SHALE   SERIES    (EARLY   TERTIARY   OR   MESOZOIC?) . 

Along  the  western  border  of  Excelsior  Flat  is  found  a  belt  of  red 
sandstone  which  underlies  the  lavas.  This  sandstone  belt  is  contin- 
uous to  the  low  mountains  south  of  here,  where  it  passes  upward  into 
a  series  of  gray  vStratified  rocks.  Farther  east  the  sandstone  series, 
with  the  overlying  gray  rocks,  seems  to  overlie  the  probable  Tertiary 
limestones  which  outcroj)  along  the  eastern  portion  of  Excelsior  Flat, 
the  older  rock  being  apparently  the  core  of  an  east- west  striking  anti- 
clinal fold,  and  the  sandstone  series  forming  the  northern  limb.  On 
the  southern  limb,  which  comprises  the  main  ridge  of  the  Excelsior 
Mountains,  the  bulk  of  the  rocks  seem,  as  viewed  from  a  distance, 
also  to  belong  to  the  stratified  red  sandstone  and  shale  series. 

Following  the  road  farther  east,  the  transverse  sjiur  which  runs 
northward  from  the  main  ridge  of  the  Excelsior  Mountains  exhibits 
the  same  east- west  striking  anticline.  Along  the  axis  a  canyon  has 
been  cut  through  the  spur,  and  here  are  exjjosed  red  sandstones,  with 
much  red,  yellow,  brown,  and  green  dense  siliceous  shales.  No  fossils 
could  be  found.  The  rocks  here  stand,  in  general,  nearly  vertical, 
and  are  crumj)led  and  faulted.  South  of  here  the  rocks  have  a 
southerly  dij),  first  steep,  then  shallowing,  while  to  the  north  the 
rocks  belonging  to  the  same  series  have  for  a  considerable  distance  a 
northerly  dip,  which  afterwards  reverses  so  that  a  body  of  underl3'- 
ing  gray  shale,  which  may  belong  to  the  probable  Tertiary  limestone 
series,  comes  into  the  visible  section. 

From  the  data  above  noted,  we  appear  to  have  a  series  of  red  sand- 
stones and  quartzites,  with  some  shales  and  conglomerates,  having  a 
roughly  estimated  thickness  of  1,500  feet.  These  are  overlain  by  a 
series  of  red -gray  sandstones,  shales,  and  conglomerates  about  2,000 
feet  in  thickness,  making  a  total  of  about  3,500  feet.     These  rocks 


SPURR.]  EXCELSIOK   KANGE.  Ill 

seem  to  overlie  the  probable  Tertiary  limestones  aud  are  folded 
together  with  them.  The  exact  contact  of  the  tAvo  series,  however, 
was  not  found.  No  such  sediments  as  this  sandstone-shale  are  known 
in  the  Paleozoic  section,  and  therefore  the  rocks  would,  without  any 
other  consideration,  at  once  be  considered  as  Mesozoic  or  Tertiary. 
In  the  region  just  south  of  here  a  series  of  folded  shales  and  tuffs 
has  been  described  by  Mr.  Turner"  under  the  name  of  the  Esmeralda 
formation  and  is  probably  Miocene,  possibly  reaching  back  into  the 
Eocene. 

This  series,  when  observed  by  the  i^resent  Avriter,  struck  him  as 
resembling  in  a  general  way  the  thin  sandstones  and  parti-colored 
shales  of  the  Excelsior  Range  section,  although  the  latter  are  dis- 
tinctly more  highly  indurated  and  altered. 

Rocks  similar  to  the  sandstone-shale  series  of  the  Excelsior  Railge 
form  a  large  portion  of  Pilot  Mountain,  just  to  the  east  of  here,  across 
Soda  Springs  Valley.  As  noted  in  the  description  of  the  Pilot  Range, 
Mr.  H.  W.  Turner  found  Jurassic  fossils  in  some  of  these  beds. 

It  is  therefore  not  certain  whether  the  sandstones  and  shales  of  the 
Excelsior  Mountains  are  Tertiary  or  Mesozoic,  and  they  may  be  partly 
one  and  partly  the  other. 

While  the  series  of  tuffs,  sandstones,  shales,  and  conglomerates  of 
the  Excelsior  Range  may  possibly  be  the  equivalent  of  the  somewhat 
similar  strata  of  the  Esmeralda  formation  near  Silver  Peak,  the  lime- 
stone of  the  former  locality  is  not  represented  in  the  latter.  This 
limestone  also  sejjarates  itself  from  the  probable  fresh- water  Esmer- 
alda formation  in  that  its  fauna  denotes  a  i3robable  marine  origin. 
In  this  respect,  also,  it  seems  to  be  different  from  the  rest  of  the  known 
Tertiary  strata,  which  extend  in  a  more  or  less  continuous  belt  from 
this  district  south  into  the  Mohave  Desert,  and  the  present  aspect  of 
our  knowledge  indicates  that  it  represents  a  period  during  which 
conditions  were  quite  different  from  those  which  followed. 

PLIOCENE. 

On  the  western  side  of  Excelsior  Flat  the  lava  is  underlain  by  a 
solid  but  friable  deposit,  consisting  of  ash  and  pumice,  having  the 
appearance  of  being  waterlaid.  This  occurs  at  an  elevation  of  about 
5,500  feet.  In  the  valley  below  and  to  the  east  of  this  are  less  con- 
solidated, horizontally  stratified  gravels,  containing  pebbles  of  lava 
and  reaching  up  nearly  to  the  same  elevation. 

On  the  eastern  flanks  of  the  Excelsior  Mountains,  overlooking  Soda 
Springs  Valley,  there  was  noted,  at  an  elevation  of  5,250  feet,  hori- 
zontally stratified  gravels  and  volcanic  tuffs,  lying  uuconformably 
against  the  folded  Tertiary  series  and  partially  consolidated.  The 
regular  stratification  of  these  deposits  suggests  that  they  are  lake 

a  Am.  GeoL,  Vol.  XXV,  1900,  p  168.    See  also  this  report,  p  185. 


112  GEOLOGY    OF    NEVADA   SOUTH    OF   40TH    PARALLEL,     [bull.  208. 

sediments,  aud  they  are  probably  to  be  correlated  with  similar  sedi- 
ments found  all  over  the  region  north  and  west  of  here,  which  have 
been  called  Pliocene. 

IGNEOUS   ROCKS. 


Along  the  road  between  Hawthorne  and  Sodaville,  which  passes 
through  Excelsior  Flat,  there  is,  on  the  west  border  of  the  hills,  a  belt 
of  fine-grained  lava,  which  forms  broad,  slightly  dissected  mesas.  A 
specimen  of  this  lava  proved  to  be  pja-oxene-olivine-basalt.  It  occu- 
pies a  large  area,  inclosing  the  body  of  probable  Tertiary  limestone, 
whicli  it  overlies,  and  toward  the  east  forms  a  considerable  portion  of 
the  main  ridge  of  tlie  Excelsior  Mountains,  of  the  spurs  which  run 
north  from  it,  and  of  the  parallel  east-west  ridge  with  which  these 
spurs  connect.  It  overlies  the  probable  Tertiary  sandstones  and 
shales  and  the  stratified,  water-laid  tuffs  and  gravels  of  the  Pliocene. 
South  of  the  main  range  the  earlier  Tertiary  series  is  again  overlain 
by  slightly  dissected  lava,  and  this  lava  runs  southward  into  the  Can- 
delaria  Mountains,  where  a  prominent  peak  has  the  aspect  of  a 
slightly  denuded  volcanic  cone. 

The  fact  that  this  lava  overlies  all  the  stratified  rocks,  even  the 
supposedly  Pliocene  gravels,  together  with  its  very  slight  erosion, 
shows  that  it  is  very  young,  probably  early  Pleistocene.  The  comi)o- 
sition  of  the  lava  bears  out  this  reasoning,  for  it  is  probably  to  be 
correlated  with  the  Pleistocene  basalts  described  in  other  ranges.*^ 

GRANITIC  ROCKS. 

As  seen  from  Excelsior  Flat,  a  considerable  portion  of  the  highest 
part  of  the  Excelsior  Mountains  to  the  southwest  consists  of  gray, 
rugged- weathering  granitic  rocks.  At  the  abrujit  eastern  end  of  the 
main  range  the  earlier  Tertiary  sandstone  and  shale  series  is  contorted 
and  apparently  cut  by  granitic  dikes. 

STRUCTURE. 

To  the  north  of  the  main  ridge,  the  general  east-west  valley,  which 
is  in  part  occupied  by  Excelsior  Flat,  seems  to  lie  along  the  axis  of  an 
anticlinal  fold  with  east-west  strike.  The  main  ridge  lies  on  the 
southern  limb  of  this  fold,  while  the  minor  ridge  lying  north  of  the 
valley  and  parallel  to  the  main  one,  is  on  the  northern  limb. 

Northwest  of  Excelsior  Flat  the  area  of  probably  Tertiary  lime- 
stone first  described^  forms  one  of  the  north-south  spurs  which  run 
at  right  angles  to  the  main  range.  The  structure  of  this  spur  is  anti- 
clinal, but  the  strike  of  the  fold  is  north  and  south. 

«J.  E.  Spurr,  Succession  and  relation  of  lavas  in  the  Grreat  Basin  region:  Jour.  Geol.,  Vol. 
VIII,  p.  636. 
b  See  p.  109. 


SPUBR]  EXCELSIOE    AND    CANDELAKIA    MOUNTAINS.  113 

ORES. 

There  lias  been  considerable  mineralization  in  the  Excelsior  Moun- 
tains. On  the  west  side,  along  the  road  traveled,  there  has  been 
mineralization  in  the  limestoue  near  the  contact  with  the  overlying 
lava.  Farther  east  the  red  sandstones  are  found  to  be  bleached  and 
to  contain  disseminated  copper  minerals.  On  the  eastern  end  of  the 
main  range  are  ore  deposits,  associated  with  crnmpling  of  the  strata 
and  probably  with  granitic  dikes. 

RESUME. 

The  rocks  of  the  mountains  are  probably  Early  Tertiary  limestones, 
together  with  a  series  of  sandstones  and  shales  with  some  conglomer- 
ates. The  relative  age  of  the  limestones  and  sandstone  shales  is 
uncertain.  These  two  series  were  folded  together.  While  the  main 
folds  trended  east  and  west,  a  minor  set  had  north-south  axes.  At 
about  the  same  time  came  the  intrusion  of  granitic  rocks  as  dikes  and 
larger  masses;  the  ore  deposition  was  also  probably  nearly  contem- 
poraneous. After  this  came  deep  and  long-continued  erosion,  bring- 
ing about  the  present  topography  and  followed  by  the  formation  of 
the  Pliocene  lake.  Finally  this  lake  receded  and  great  sheets  of 
basalt  were  poured  out. 

CANDELARIA  MOUNTAINS. 

The  term  Candelaria  Mountains  is  here  applied  to  an  irregular 
group,  reaching  from  the  California-Nevada  State  line  eastward  to 
the  Columbus  Valley.  It  lies  Just  north  of  the  White  Mountain 
range  and  south  of  the  Excelsior  Mountains. 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

Mr.  F.  B.  Weeks,  who  visited  the  mountains  in  1899,  has  informed 
the  writer  of  the  existence  of  a  considerable  thickness  of  quartzite 
and  limestone  (see  PL  I).     No  identifiable  fossils  were  found. 

CARBONIFEROUS. 

On  the  road  between  Columbus  and  Candelaria  there  occnr  dark- 
graj^  nearly  black,  quartzites,  and  stretched  conglomerates,  with 
some  coarse  sandstones  and  nearly  white  fine-grained  chert.  Mr. 
H.  W.  Turner  has  kindlj^  supplied  the  writer  with  the  following  note 
concerning  the  disco veiy  of  Carboniferous  fossils  in  this  rock: 

I  am  indebted  to  William  Grozenger  for  information  as  to  tliis  locality,  which 
lies  3  miles  northwest  of  Columbus  by  the  trail  to  Candelaria,  at  an  elevation  of 
about  4,900  feet.     Similar  fossils  also  occur  in  the  gulch  just  north  of  this  point  at 

Bull.  208—03 8 


114  GEOLOGY    OF   NEVADA   SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

an  elevation  of  aboiit  5,300  feet.  These  fossils  were  referred  to  Mr.  Charles  Schu- 
chert,  of  the  United  States  National  Museum,  who  reports  that  the  collection 
contains  two  Carbonic  species,  a  Productus  and  a  Spirifer.  Both  are  specifically 
tindeterinined  at  present.  The  Spirifer  (apparently  a  new  species)  belongs  to  the 
S.  eavieratus  section,  fossils  recognized  as  characteristic  of  the  Upper  Carbonic. 
The  Productus  is  apparently  identical  with  one  from  the  region  north  of  Mount 
Shasta,  in  California,  also  associated  with  Upper  Carbonic  species.  These  forms 
remind  one  more  of  the  Carboniferous  fauna  found  in  the  Shasta  region  than  of 
the  Carboniferous  farther  east. 

EARLIER  TERTIARIES. 

Adjoining  the  Carboniferous  rocks  to  the  northeast,  and  probably 
overlying  them  is  a  comparatively  small  area  of  brown,  yellow,  some- 
times purplish,  limy  and  sandy  shales,  argillaceous  fine  sandstones, 
and  thin-bedded  brown  and  yellow  aphanitic  limestones.  This  series 
strikes  N.  65°  E.,  and  dips  65°  NW.  It  is  probably  identical  with 
the  rocks  of  the  Esmeralda  formation  a  few  miles  to  the  south,  In  the 
southern  end  of  the  Monte  Cristo  Mountains.  At  one  place  the 
upturned  edges  of  the  stratified  rocks  are  overlain  by  a  thin  sheet  of 
siliceous  rock,  so  glassy  that  the  microscope  does  not  show  its  true 
character,  but  it  is  probably  rhyolite  and  susceptible  of  correlation 
with  the  rhyolite  overlying  the  sedimentary  rocks  in  the  Monte  Cristo 
Mountains. 

PLIOCENE  BEDS. 

At  the  gap  which  separates  the  Pilot  Mountains  from  the  Cande- 
laria  Mountains,  just  north  of  Candelaria,  occur  certain  horizontally 
stratified  clays  and  sands  which  have  already  been  mentioned,  in 
describing  the  Pilot  Mountains,  as  belonging  to  the  group  of  Pliocene 
sediments. 

IGNEOUS  ROCKS. 

Overlying  the  Pliocene  sediments  not  far  north  of  Candelaria,  thin 
sheets  of  olivine-basalt  were  found  (Pleistocene).  South  of  liere,  over- 
lying the  stratified  beds  of  the  Esmeralda  formation,  were  found  the 
sheets  of  glassy  rhyolite  above  mentioned.  West  of  Columbus  and 
Candelaria,  a  large  part  of  the  range  appears  to  be  comj)osed  of  red 
and  gray  lavas  overlying  and  often  concealing  the  sedimentary  rocks. 
As  seen  from  Sodaville,  the  northern  part  of  this  mountain  group  is 
also  chiefly  volcanic,  the  topography  showing  such  smooth,  mesa-like 
forms,  and  so  little  erosion  that  the  rocks  were  considered  as  probabl}^ 
belonging  to  the  Pleistocene  lavas.  A  prominent  peak  in  the  central 
portion  of  the  Candelaria  Mountains  has  the  aspect  of  a  little  denuded 
volcanic  cone." 

a  These  observations  have  been  confirmed  by  Messrs.  Turner  and  Weeks,  who  visited  the  range 
separately  the  same  year  as  did  the  writer.  Mr.  Turner  states  that  the  bills  north  of  Benton 
are  also  all  lavas. 


SPURR.]  RANGES    OF    WEST-CENTEAL    NEVADA.  115 

WALKER  RIVER  RANGE. 

The  Walker  River,  or  Wassiiek,  Range  is  a  straight,  bold  ridge  of 
mountains,  rising  immediately  from  the  west  shore  of  Walker  Lake. 
It  has  a  trend  a  little  west  of  north  and  a  length  of  about  (50  miles. 
It  is  separated  on  the  north  from  the  volcanic  Desert  Mountains  by 
the  Walker  River  Valley,  and  on  the  south  it  passes  into  the  irregular 
Excelsior  Mountains.  Throughout  most  of  its  course  the  range  is 
characterized  by  the  comj)aratively  gentle  slope  of  the  west  side  and  a 
steep  scarp  on  the  east. 

IGNEOUS   ROCKS. 

Almost  all  the  rocks  of  the  Walker  River  Range  are  igneous.  Those 
on  the  steep  eastern  face  are  generally  granular,  and  those  on  the 
west  side  typical  volcanics. 

GRANULAR  ROCKS. 

Just  west  of  the  Indian  agency  at  the  upper  end  of  Walker  Lake, 
the  rock  of  the  mountains  is  chiefly  a  coarse-grained  biotite-granite. 
Farther  north,  near  the  point  where  the  road  crosses  the  range, 
biotite-granite-aplite,  of  a  distinctly  more  siliceous  variety  than  the 
first,  occurs  in  conjunction  with  great  masses  of  alaskite-aplifce. 

On  the  road  which  crosses  the  range,  at  a  point  southwest  of  Haw- 
thorne, the  summit  and  greater  part  of  the  mountain  range  appears 
to  be  also  of  decomjiosed  biotite-granite.  Between  these  two  locali- 
ties the  granite  is  i^robably  nearly  or  quite  continuous. 

Underlying  the  biotite-granite,  at  the  point  first  described,  is  a  dark 
rock,  specimens  of  which  proved  to  be  hornblende-quartz-syenite  and 
biotite-hornblende-quartz-monzonite.  The  granite  is  shown  by  its 
branching  dikes  to  be  intrusive  into  the  more  basic  rock.  Both  rocks 
are  cut  by  dikes  of  alaskite,  which  grows  very  siliceous  and  runs  out 
in  places  to  nearly  pure  quartz. 

In  the  cream-colored  mountain  of  granite  and  alaskite  around 
which  the  road  turns  in  crossing  the  range,  the  alaskite  is  evidently 
younger  than  the  siliceous  granite,  into  which,  however,  it  x^asses  by 
transitional  stages  as  regards  its  composition.  The  granite  some- 
times contains  large  feldspar  phenocrysts,  similar  to  those  of  the  rock 
near  Belmont  and  near  Ellsworth. 

At  the  pass  southwest  from  Hawthorne,  the  biotite-granite  which 
occupies  the  summit  of  the  mountains  is  succeeded  farther  east  by 
metamorphosed  igneous  rocks,  probably  altered  by  dynamic  move- 
ments. These  rocks  lie  along  the  face  of  a  bold,  eastward-facing 
scarp.  As  examined  microscopically,  they  consist  of  aposyenite-por- 
phyry,  apogranite,  and  apoalaskite,  with  some  biotite-rhyolite,  which 
may  be  later  than  the  others.  These  metamorphosed  igneous  rocks 
are  confused  with  some  highly  altered  limestones  and  quartzites. 


116  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH    PAEALLEL.     [bull.308. 


On  the  west  side  of  the  cream-colored  mountain  which  lies  north- 
west of  the  north  end  of  Walker  Lake,  on  the  road  across  the  range, 
the  granular  rocks,  already  described,  pass  under  and  into  gray  and 
red  volcanics,  which  dip  30°  to  45°  SW.  away  from  the  mountain. 
About  the  point  where  the  granular  rock  gives  place  to  the  evident 
volcanics,  specimens  were  collected,  which  proved  to  be  alaskite- 
IDorphjay  and  tordrillite,  the  latter  with  a  finely  cryptocrystalline 
groundmass.  Overlying  these  siliceous  rocks  was  found  augite-biotite- 
aleutite.  West  of  this  point,  near  the  summit  of  the  range,  the  prev- 
alent rock  is  biotite-andesite,  containing  many  angular  fragments  of  a 
darker  lava.     The  whole  western  side  of  the  mountains  is  volcanic. 

IGNEOUS  ROCKS  SHOWING  TRANSITIONS   OF  TEXTURE. 

In  a  small  butte  (Mason  Butte)  which  emerges  from  the  Pleisto- 
cene valley  deposits  to  the  west  of  the  northern  part  of  the  Walker 
River  Range,  a  few  miles  south  of  Wabuska,  an  intersecting  series  of 
igneous  rocks  was  studied.  The  butte  presents  the  appearance  of  a 
typical  volcanic  rock,  being  distinctl}^  and  thinly  bedded  and  of  red 
and  gray  colors. 

Upon  examination  the  rocks  are  found  to  be  in  part  granular  and  in 
part  fine  grained  and  j)orphyritic,  the  different  textures  alternating 
in  conformable  beds.  Examined  microscopicallj',  the  coarse-grained 
rocks  are  hornblende-biotite-quartz-diorites,  while  the  fine-grained 
ones  are  hornblende-biotite-quartz-andesites.  The  chemical  composi- 
tion of  the  two  rocks  is  also  nearly  the  same.  Sometimes  the  coarse- 
grained and  the  fine-grained  types  api^ear  in  the  same  bed,  one 
apparently  being  formed  at  the  same  time  as  the  other;  generally, 
however,  the  beds  are  separate. 

The  hyj)othesis  adopted  by  the  writer  is  that  these  rocks  are  the 
roots  of  old  volcanic  flows  which  have  been  exposed  by  the  removal 
of  the  overlying  portions  of  the  lava  through  the  erosion  of  Walker 
River,  in  whose  valley  the  butte  lies.  The  whole  appears  to  have 
been  an  igneous  mass  in  process  of  slow  flowage,  some  streaks  of 
which  crystallized  rapidly,  with  the  texture  of  true  lavas,  while 
between  them  portions  of  the  same  magma  crystallized  more  slowly, 
as  granular  rocks.'* 

Facts  suggesting  similar  transitions  of  texture  were  noted  within 
the  main  Walker  River  Range,  but  are  not  described  on  account  of 
insufficient  evidence. 

SEDIMENTARY   ROCKS. 

PLEISTOCENE. 

Professor  Russell  lias  described  the  history  ^  and  the  sediments  of 
the  Pleistocene  Lake  Lahontan,  an  arm  of  which  occupied  the  valley 

a  For  a  fuller  statement  of  this  problem  see  J.  E.  Spiirr,  Variations  of  texture  of  certain  Terti- 
ary igneous  rocks  in  the  Great  Basin:  Jour.  GeoL,  Vol.  IX,  p.  586. 
6 Men.  U.  S.  Geol.  Survey  Vol.  XI, 


SPURR]  WALKER   RIVER    AND    SMITH    VALLEY    RANGES.  117 

of  the  present  Walker  Lake.  The  writer  also  observed  these  sedi- 
ments as  well  as  older  stratified  deposits,  which  reach  higher  up 
in  the  mountains.  The  line  between  the  Pleistocene  and  the  Tertiary 
has  not  been  closely  di-awn  in  this  region,  and  probablj^  a  portion  of 
those  dej)Osits  older  than  the  Lahontan  sediments  are  still  Pleisto- 
cene, but  at  present  the  writer  will  include  under  that  head  only  the 
deposits  of  the  lake  described  b}^  Russell. 

In  the  valley  of  Walker  Lake  the  dej)tli  of  the  Pleistocene  Lake 
Lahontan  at  its  highest  stage  was  225  feet.  At  the  upper  end  of  the 
present  Walker  Lake  the  elevation  is  4,120  feet  above  sea  level,  which 
would  make  the  surface  of  Lake  Lahontan  at  this  iDoint  4,845  feet. 
At  about  this  altitude,  as  measured  by  the  barometer,  the  writer 
found  a  heavy  terrace,  and  about  200  feet  above  this  a  still  heavier 
one,  the  top  of  the  main  terrace  being  about  4,600  feet  high.  These 
terraces  are  constructional  and  show  a  rude  horizontal  stratification. 
They  are  composed  largely  of  gravels  and  huge  bowlders  from  the 
adjacent  mountains.  At  another  point,  farther  north,  the  altitude  of 
this  same  chief  terrace  was  determined  as  4,675  feet.  On  tlie  opposite 
side  of  the  valley,  on  the  slopes  of  the  Painted  Mesa  (which  forms 
part  of  the  Desert  Mountains),  corresponding  dej)osits  may  also  be 
seen,  taking  the  form  of  inclined  slopes  or  ancient  beaches  rather 
than  of  sharpl}^  cut  terraces. 

PRE-LAHONTAN  SEDIMENTS. 

About  100  feet  above  the  heaviest  terrace  just  mentioned  is  a 
lesser  constructional  terrace,  and  about  400  feet  higher  there  is  on 
the  mountains  a  rock-cut  bench  which  is  probably  also  a  water  line. 
This  rock-cut  bench  is  at  an  altitude  of  about  5,100  feet,  or  about  700 
feet  above  the  surface  of  the  ancient  Lake  Lahontan,  while  the  con- 
structional terrace  below  it  is  about  300  feet  above  the  old  surface. 
Crossing  the  southern  end  of  the  range,  coarse,  horizontally  stratified 
material,  consisting  of  little  assorted  volcanic  rock,  is  found  to  the 
summit,  where  it  forms  hills  400  or  500  feet  high,  reaching  up  to  an 
altitude  of  about  5,730  feet,  or  1,385  feet  above  the  surface  of  Lake 
Lahontan. 

On  the  western  side  of  the  range,  at  the  point  where  the  road  crosses 
due  southwest  from  Hawthorne,  stratified  gravels  are  found  u]3  to  a 
height  of  7,100  feet.  These  deposits  seem  to  be  water-laid.  They  are 
evidently  pre-Lahontan,  and  if  formed  in  a  lake  occupied  a  body  of 
Avater  which  was  the  ancestor  of  the  Pleistocene  lake,  but  of  vastlj 
greater  dimensions  and  probabl}^  of  longer  life. 

From  reasons  entailed  in  the  correlation  of  these  gravels  with  others 
throughout  the  region  these  deposits  are  provisionally  classified  as 
Pliocene. 

SMITH  VALLEY  RANGE. 

The  name  Smith  Valley  Range  may  be  applied  to  a  low  and  narrow 
moF  ntain  ridge,  which  on  the  north  merges  Avith  the  Pine  Nut  Range, 


118  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

and  on  the  south  spreads  out  broadly  into  a  series  of  volcanic  mesas, 
which  connect  farther  south  with  a  spur  of  the  Sierras  north  of  Lake 
Mono.  The  range  as  thus  defined  separates  Mason  Valley,  on  the  east, 
from  Smith  Valley,  on  the  west. 

IGNEOUS   ROCKS. 

Smith  Valley  Range  is  essentially  volcanic.  At  the  northern  end, 
where  it  merges  into  the  Pine  Nut  Range,  specimens  of  the  lava,  form- 
ing comparatively^  well-dissected  mountains,  are  found  to  consist  of 
hypersthene  and  biotite-andesite,  with  some  biotite-dacite.  South- 
ward from  here  the  range  is  evidently  volcanic,  but  it  was  not  examined 
closely  except  in  the  region  of  Dalzell  Canyon,  which  separates  the 
southern  part  of  the  range  tro^n  the  Sweetwater  Mountains,  fai'ther 
west. 

In  Dalzell  Canyon  the  oldest  formation  consists  of  granite  and 
rhyolite,  and  is  altered  and  jointed.  Overlying  this  is  iJja^oxene- 
hornblende-andesite,  and  still  higher  are  comparatively  slightly  eroded 
mesas  of  more  siliceous  andesitic  rock,  or  hornblende-biotite-latite. 

On  the  road  which  cuts  across  the  low  southern  end  of  the  range 
east  of  Sweetwater,  following  the  upper  part  of  the  East  Walker 
'River  Valley,  the  siliceous  andesite  and  latite  flows  are  succeeded  on 
the  east  by  more  basic  thin-bedded  andesitic  or  basaltic  lava,  largely 
glassy.  This  overlies  sands,  clays,  and  conglomerates,  which  will 
presently  be  described  as  probably  Pliocene.  It  has  flowed  into  and 
dammed  up  the  valley  eroded  in  the  earlier  lavas.  It  is  therefore  the 
latest  of  all  and  is  i^robably  Pleistocene.  Farther  east  this  same 
glassy  lava  occupies  a  considerable  area  in  the  bottom  of  the  broad 
Walker  River  Valley,  and  forms  broad  mesas  on  the  flanks  of  the 
Smith  Valley  Range  on  f he  west  and  the  Walker  River  Range  on  the 
east,  and,  reaching  around  to  the  south,  forms  a  large  part  of  the  hills 
between  the  Walker  River  Vallej^  and  Mono  Valley.  At  the  southern 
end  of  Walker  River  Valley,  a  few  miles  north  of  Auroi-a,  is  a  little- 
defaced  volcanic  cone  of  red  lava,  which  probajbly  belongs  to  the  same 
epoch.  This  has  been  called  the  Aurora  Crater  on  the  topographic 
map  accompanying  Professor  Russell's  paper  on  Lake  Mono.^'  These 
lavas  everywhere  overlie  the  stratified  gravels  which  occur  in  the 
southern  part  of  the  Walker  Lake  Valley,  in  the  same  manner  as 
already  mentioned. 

South  of  here,  in  the  basin  of  Lake  Mono,  Professor  Russell*  has 
described  various  lavas,  including  hypersthene- andesite  verging  upon 
basalt,  and  rhy9lite,  which  are  evidently  Pleistocene.  These  lavas 
belong  to  the  same  class  as  those  just  described,  and  seem  to  corre- 
spond with  the  thin  flows  capping  the  Pliocene  gravels  near  Welling- 
ton on  the  Sweetwater  Range,  and  also  to  the  thin  flow  of  basalt  which 

a  Eighth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  PI.  XVII. 
6  Ibid.,  pp.  374,  375,  377,  380. 


SPURR]  SMITH    VALLEY    RANGE.  119 

constitutes  the  latest  volcanic  rock  in  Eldorado  Canj^on  in  the  Pine 
Nut  Range;**  hut  in  the  district  under  immediate  consideration  we 
have  a  vastly  greater  amount  of  Pleistocene  volcanic  action  than  was 
ohserved  anywhere  else  in  the  region. 

SEDIMENTARY  ROCKS. 

Just  south  of  Dalzell  Canyon  were  found  well-stratified  arkoses 
and  little- worn  conglomerates,  containing  chiefly  angulai-  fragments. 
These  seem  to  cover  the  whole  of  a  broad  upland  valley,  to  its  abrupt 
end  at  the  base  of  the  Sweetwater  Mountains,  at  an  elevation  of  some- 
thing over  7,000  feet.  As  one  goes  southeastward  from  here,  i^assing 
Sweetwater  post- office  and  proceeding  down  the  valley  of  Walker  River 
where  this  cuts  across  the  range,  one  finds,  at  an  elevation  of  6,500 
feet  at  least,  and  below,  well-stratified,  washed,  and  assorted,  hori- 
zontally or  slightly  cross-bedded  sandstones,  arkoses,  and  gravels. 
These  rocks  are  often  firmly  consolidated,  though  friable,  and  resem- 
ble the  sandstones  near  Carson,  as  exposed  at  the  State  prison.*  The 
pebbles  in  the  gravels  are  evidently  derived  from  tlie  andesite  which 
is  the  main  rock  of  the  Smith  Vallej^^  Range.  Farther  west,  on  the 
slopes  of  the  hills  facing  the  main  Walker  River  Vallej*,  a  section  of 
these  deposits  100  feet  thick  was  examined.  Near  the  bottom  were 
found  sandy  clays,  which  may  be  in  part  water-laid  volcanic  ash. 
Farther  up  come  hard  gravels,  the  well-rolled  pebbles  comi)rising 
various  varieties  of  hornblende-  and  mica-andesite.  Above  this  comes 
a  compact  gray  sandstone,  also  made  ux3  of  volcanic  debris  and  contain- 
ing fragments  of  white  decomposed  pumice.  Capping  the  sedimen- 
tary rocks  and  overlying  them,  with  a  considerable  angle  of  divergence, 
comes  a  thin  sheet  of  andesitic  or  basaltic  lava  with  glassy  base.  The 
top  of  this  section  has  an  altitude  of  about  0,150  feet.  A  short  dis- 
tance away  from  this  section  the  highest  sandstone  reaches  an  altitude 
of  about  6,350  feet  and  is  exposed  as  a  simple  bench  in  the  mountains, 
the  overlying  lava  having  been  eroded  back  from  it.  Along  the  north- 
ern slopes  of  the  mountains  which  form  the  southern  end  of  the  Walker 
River  Valley,  northwest  from  Aurora,  are  continuous  benches,  the 
best  marked  of  which  can  be  little  less  than  7,000  feet  in  height. 
Below  this  are  other  sharp  smooth  benches  of  horizontal  sandstone. 
The  comparatively  recent  volcanic  cone  above  referred  to,  lying  north- 
east from  Aurora,  is  benched  up  to  6,700  or  6,800  feet,  but  not  higher. 
These  terraces  appear  to  grow  somewhat  higher  to  the  south.  The 
whole  valley  here  is  covered  with  the  sandstones  above  described, 
which  have  been  considerably  eroded.  At  least  700  or  800  feet  of  this 
sedimentarj^  series  is  exposed. 

On  the  road  which  crosses  the  southern  end  of  the  East  Walker 
River  Valley  and  goes  over  the  Walker  River  Range  to  Hawthorne, 

a  See  pp.  121  and  126.  b  See  p.  124. 


120  GEOLOGY    OF    TSTEVADA  SOUTH    OF   40TH    PARALLEL,     [bull.208. 

horizontally  stratified  gravels,  apparently  belonging  to  the  same  series 
as  the  sandstones  above  mentioned,  occnr,  frequently  overlain  b}'' 
glassy  and  slaggy  andesitie  or  basaltic  lavas,  up  to  a  height  of  7,100 
feet,  where  they  give  way  to  a  fresh  lava,  above  which  all  is  decom- 
posed granite. 

All  these  comparatively  recent  horizontal  sediments  are  provision- 
ally^ classed  as  Pliocene. 

PINE  NUT  RANGE. 
TOPOGRAPHY. 

The  Pine  Nut  Range  lies  immediately  east  of  the  Sierra  Nevada, 
and  has  much  of  the  bold  irregular  topograph}^  of  that  range.  As 
contrasted  with  the  mountains  of  the  more  arid  regions  farther  east, 
it*  is  distinguished  by  deeper  dissection,  affording  more  profound 
canyons  and  more  abrupt  cliffs.  The  eastern  face  of  the  range  is 
steep,  the  western  side  in  general  less  abrupt. 

Wherever  this  range  was  visited,  numerous  springs  were  observed, 
and  the  dissection  seemed  to  be  largely  the  result  of  water  derived 
from  these  sources.  The  springs  seem  to  be  arranged,  in  part  at 
least,  along  north-south  lines,  which  are  probably  lines  of  fracture. 
These  lines  are  deeper  than  the  regions  between,  Avhich  stand  up  as 
ridges;  but  whether  these  ridges  are  directly  due  to  displacement,  or 
have  been  left  as  such  by  the  erosion  of  depressions  along  the  lines  of 
spring  water,  is  uncertain. 

On  the  western  side,  between  Daj^ton  and  Carson,  the  peculiarlj' 
wild  and  rugged  topograi:)hy  is  caused  bj^  the  Carson  River  and  its 
mountain  tributaries  which,  in  late  Tertiarj^  or  Pleistocene  time,  have 
dissected  the  mountain  and  the  adjacent  plateau-valle3^ 

IGNEOUS  ROCKS. 

Nearly  the  whole  mass  of  the  range  is  igneous.  The  rocks  Avere 
studied  principally  along  two  sections,  one  across  the  range  southeast 
from  Dayton  and  the  other  on  the  road  between  Wellington  and 
Genoa. 

In  the  eastern  part  of  the  first-mentioned  section,  in  the  loAver 
mountains  which  here  lie  to  the  east  of  the  main  range  and  are  con- 
nected with  the  northern  end  of  the  Smith  Vallej^  Range,  chiefly 
andesitie  rocks  were  found.  The  andesite  contains  different  ferro- 
magnesian  minerals,  including  hornblende,  augite,  hypersthene, 
bronzite,  and  biotite.  Occasionally  biotite-dacite  or  quartz-andesite 
is  found.  Where  erosion  has  cut  deeply  into  the  lava,  coarser,  denser, 
more  massive,  and  more  porjjhyritic  forms  are  exposed.  At  the  bot- 
tom of  one  of  these  canyons  the  lava  is  a  fine-grained  diorite-porphyry, 
while  farther  up  it  is  hypersthene-bronzite-andesite  with  some  dacite. 

Farther  west,  on  the  eastern  scarp  of  the  main  range,  occur  gran- 


SPURR]  PINE    NUT    EANGE.  121 

iilar  I'ocks.  These,  when  examined  microscopically,  tnrned  ont.  to  be 
hornblende-biotite-granite,  sometimes  porphyritic,  and  alaskite.  The 
same  granular  siliceous  rocks  are  exposed  nearly  to  the  summit,  and 
they  occur  also  on  the  western  side  of  the  divide.  Here  they  are 
overlain  by  hornblende-,  augite-,  and  hypersthene-andesites. 

About  halfway  down  the  mountains,  in  Eldorado  Canyon,  where 
the  road  leading  to  Dayton  runs,  there  are  hills  of  gently  folded  grav- 
els and  coarse  clays,  the  gravels  being  derived  almost  entirely  from 
the  andesites.  They  are  exposed  best  in  the  arroyos,  where  they  are 
overlain  unconformablj^  hy  8  or  10  feet"  of  stratified  bowlders  and  soil, 
which  represent  the  recent  stream  accumulations.  Farther  doAvn  the 
canyon  is  a  volcanic  breccia  with  rounded  andesite  bowlders,  prob- 
ablj^  water-laid.  This  breccia  is  followed  by  thin  flows  of  slaggy  white 
lava,  which  contains  numerous  included  angular  fragments  of  andes- 
ite; these  flows  are  interbedded  with  ash.  The  present  canyon  has 
been  worn  down  through  this  breccia,  ash,  and  porous  white  lava 
deposit.  In  several  places  a  thin  sheet  of  basalt  has  been  poured  ont 
after  the  development  of  the  present  topography  (fig.  8).     This  sheet 


Fig.  8.— Section  of  Eldorado  Canyon,  Pine  Nut  Range. 
1.  Stratified  rhyolite  ash.  2.  Basalt. 

also  occupies  the  tops  of  some  of  the  neighboring  hillocks,  which  have 
been  separated  from  one  another  by  erosion  subsequent  to  the  last 
volcanic  outbursts. 

In  the  canyon  of  the  Carson  River,  a  few  miles  southwest  of  Dayton, 
the  stream  has  cut  down  400  to  800  feet,  exposing  lavas  like  those  in 
Eldorado  Canj^on.  The  uppermost  of  these  flows  is  a  Avliite,  little- 
compacted  rhj^olite,  while  beneath  it  are  large  masses  of  a  rock  recog- 
nized in  the  field  as  lava,  which  on  microscopic  examination  appears 
to  be  monzonite-porphjay.  This  is  perhaps  a  coarser  variation  of 
andesite. 

Between  Dayton  and  Wellington  the  Pine  Nut  Range  is  mainly 
igneous.  The  central  ridge  has  a  massive  aspect  in  general,  and  is 
probably  made  up  of  the  granitic  rocks. 

Where  the  road  between  Genoa  and  Wellington  crosses  the  range, 
hornblende-biotite-andesites  occur  on  the  western  slopes.  As  in 
Eldorado  Canyon,  the  whole  system  of  gulches  has  been  cut  in  this 
lava. 


122  GEOLOGY    OF    NEVADA  SOUTH    OP   40TH    PAEALLEL.     [bull.208. 

Near  the  summit  of  the  low  pass  on  this  road  were  found  cliffs  of 
a  dense,  massive,  volcanic  breccia  with  horizontal  bedding  and  con- 
taining pebbles  of  rhyolite  only.  Some  distance  farther  up,  appar- 
ently belonging  to  the  same  series  as  the  breccia,  was  found  an  ancient, 
apparently  water-laid  tuff,  which  microscopic  examination  shows  to 
be  rhyolitic,  with  above  it  a  bed  of  coarse  volcanic  grit,  and  still 
higher  a  bed  of  volcanic  conglomerate  with  large  well-rounded  pebbles 
of  biotite-rhyolite  and  a  matrix  derived  from  the  same  rock.  A  short 
distance  farther  the  rocks  from  which  these  detritals  are  derived  were 
found  in  place  in  a  hill  to  the  north  of  the  valley  and  to  the  east  of 
the  pass.  This  rock  shows  many  and  great  variations,  passing  from 
a  fine-grained  aphanitic  rhyolite  to  coarse  granite  and  alaskite,  and 
these  variations  are  .arranged  in  thin  bands. 

These  are  essentially  quartz-feldspar  rocks,  generall}"  containing 
biotite.  They  comprise  biotite-rhyolite,  fine-grained  granite-porphyry, 
medium-grained  biotite-granite,  coarse-grained  alaskite  and  granite- 
aplite,  and  one  sjpecimen  was  a  fine-grained  quartz-monzonite-porphyry. 
These  different  varieties  present,  textn rally  and  structurally,  almost 
perfect  transitions  from  one  to  another,  ranging  from  coarse  granites 
through  the  granite-aplites  and  porphyries  to  the  rhyolite,  and  the 
development  of  the  different  structures  from  the  fine-grained  rhj^olite 
is  very  clear  and  instructive.  Only  one  band  was  found  which  did 
not  belong  to  the  general  granitic  series.  This  was  a  band  of  dark- 
green  slaty  rock,  which,  when  examined,  proved  to  be  probably  horn- 
blende-andesite;  j^et  this  rock  does  not  appear  to  be  intrusive,  but 
to  form  a  band  or  streak  probably  contemporaneous  with  the  more 
siliceous  rocks. 

West  of  this  old  granite-rhyoiite  area,  andesite  comes  in  above  it 
again,  of  the  same  kind  as  before.  Where  it  has  been  deeplj^  eroded 
a  coarser-  textural  type  is  exposed;  for  example,  the  hornblende- 
andesite  with  cryptocrystalline  groundmass,  which  represents  the 
rocks  near  the  surface,  gives  way  in  some  deeper  cuts  to  hornblende- 
andesite  with  granular  groundmass,  which  is  transitional  to  horn- 
blende-diorite-porphyry, 

SEDIMENTARY  ROCKS. 

TRIASSIC   LIMESTONE. 

Southeast  of  Dayton,  limestone,  in  extremely  scanty  outcrops,  just 
visible  beneath  the  overlying  volcanics,  was  found  on  both  sides  of 
the  range.  On  the  eastern  side  the  limestone  is  massive,  dark-blue 
and  sometimes  siliceous.  Its  laminae  are  vertical,  although  they  may 
result  more  from  shearing  than  from  stratification.  It  is  cut  by 
andesite  dikes.  On  the  western  side  of  the  mountain,  in  Eldorado 
Canyon,  the  limestone  is  also  blue  and  siliceous,  changing  to  shaly 
and  carbonaceous.     It  is  crushed  and  seamed,  but  ajDpears  nearly 


SPURR.l 


PINE    KUT   RANGE. 


123 


horizontal.     The  shal}^  limestone  contains  nearly  obliterated  fossils, 
npon  which  Mr.  T.  W.  Stanton  comments  as  follows: 

The  collection  *  *  *  yielded  only  fragments  and  impressions  of  a  Pecten 
and  a  specimen  that  appears  to  be  part  of  an  Ammonite.  These  are  Mesozoic  and 
probably  Triassic. 

This  locality  is  probably  the  same  as  that  mentioned  by  Whitney'* 
as  having-  yielded  the  Triassic  fossil  Goniatites  Icevidorsatus  Ilauer. 

This  Triassic  limestone  is  probablj^  to  be  correlated  with  King's 
Triassic  Star  Peak  limestone.* 

In  the  Pine  Nut  Range  the  limestone  is  probably  older  than  the 
granitic  rock  which  forms  the  main  range,  between  its  two  outcrops. 


Scale 


10  feet 


Fig.  9.— Sketch  section  of  wall  of  arroyo  in  bottom  of  Eldorado  Canyon,  Pine  Nut  Range. 

1.  Gravels  (pebbles  mostly  andesite)  with  coarse  clays  (Plio- 

cene—Shoshone  lake  sediments?) .    Tilting  probably  local. 

2.  stratified  bowlders  and  earth  (Pleistocene). 

for  it  contains  no  granitic  detritus.     The  granite  must  have  burst  up 
through  the  limestone  in  a  great  belt. 


PLIOCENE   DEPOSITS. 

On  the  west  flanks  of  the  mountains  above  Dayton,  as  already 
described,  there  are  found  some  hardened,  well-stratified  gravels 
and  clays,  derived  from  the  andesites,  and  overlain,  often  unconform- 
ably,  by  stream  gravels  (fig.  9).  They  have  the  appearance  of  having 
been  deposited  in  moving  water,  but  this  aspect  may  well  have  resulted 
from  current  action  in  a  stable  water-bod5^  On  the  face  of  the  range 
just  east  of  Daj- ton  there  is  a  rough  inclined  plane  running  uj^  to  a 
height  of  6,000  feet  and  terminating  in  obscure  benches.  Above  this 
termination  the  mountain  rises  sharply  and  steeply,  as  vnsij  be  seen 
on  the  Carson  topographic  sheet  j)ublished  by  the  U.  S.  Geological 

aGeol.  Sm-v.  California;  Vol.  I,  p.  459.         bU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.  270. 


124  GEOLOGY    OF    NEVADA.  SOUTH    OF   40TH    PAEALLEL.     [bull. 208. 

Survey.  The  approximately  horizontal  upper  limit  of  the  plane  sug- 
gests lake  action,  and  the  older  gravels  and  clays  in  Eldorado  Canyon 
strengthen  the  idea.  At  Dayton  Professor  Russell'' has  placed  the 
limit  of  one  of  the  bays  of  Lake  Lahontan  at  an  elevation  of  4,375 
feet.  The  above-mentioned  bench  is,  therefore,  1,625  feet  above  the 
uppermost  limit  of  the  Pleistocene  lake.  Southward  from  Dayton 
the  leveled  plane  was  not  observed,  and  it  is  probable  that  some  of 
the  lavas  which  here  form  the  mountain  flanks  were  laid  down  in  the 
lake  period  and  so  covered  the  ]3lane  or  prevented  its  erosion. 

In  the  plateau  valley  between  Dayton  and  Carson  there  occur 
stratified  clays  and  coarse  gravels,  at  heights  of  several  hundred  feet 
above  the  Pleistocene  Lake  Lahontan.  Near  Carson  there  occurs  a 
hardened  sandstone  or  granitic  arkose,  which  is  well  exposed  at  the 
State  prison.  The  rock  here  contains  plant  remains  and  occasional 
fresh-water  shells.  One  of  these  shells  submitted  to  Dr.  W.  H.  Dall 
was  determined  as  Anodonfa,  belonging  to  a  recent  species  found 
living  in  California.  Dr.  Dall  adds  that  the  species  may  be  older 
than  the  Pleistocene,  since  the  genus  goes  back  as  far  as  the  Eocene; 
but  that  since  the  genus  is  so  easily  affected  by  environment,  the  same 
species  is  rarely  found  in  more  than  two  horizons.  Excavations  in 
this  rock  at  the  State  prison  have  brought  to  light  layers  covered  with 
footprints  of  the  extinct  elephant  and  other  mammals  and  birds.  On 
the  hill  south  from  the  prison  there  is  benching  up  to  a  height  of  4,850 
feet.  The  same  sandstone  as  shown  at  the  State  j)rison,  but  some- 
what looser  and  more  friable,  occurs  west  of  Carson  at  the  foot  of  the 
Sierras.^ 

South  of  this  point,  along  the  face  of  the  range,  there  is  a  belt  of 
low  hills  often  covered  \\\)  bj^  the  Pleistocene  detritus,  but  consisting, 
when  exposed,  of  stratified  sands  and  gravels.  On  the  western  face 
of  the  Pine  Nut  Range,  southward  from  Carson,  there  is  generallj'^ 
visible  a  distinct  line  in  the  topograi)hy  at  about  6,000  feet,  below 
which  the  slopes  are  gentler  and  above  which  the  mountains  are 
steeper  and  more  rugged.  Along  the  road  which  crosses  the  range 
from  Genoa  to  Wellington  stratified  sands  and  gravels,  carrying  well- 
rounded  pebbles,  occur  in  hills  covering  the  gentlj^  inclined  plain  at 

aMon.  U.  S.  Geol.  Survey,  Vol.  XI,  PL  XLVI. 

ft  After  writing  the  above  description  the  writer  found  that  the  locality  had  been  already 
better  described  by  Professor  Le  Conte  and  others.  He  lets  his  own  description  stand  only  to 
show  how  independent  observations  have  led  to  similar  conclusions. 

Professor  Le  Conte  (On  certain  remarkable  tracks,  found  in  therocksof  Carson  quarry:  Proc. 
Cal.  Acad.  Sci.,  Aug.  27, 1882)  describes  a  few  fresh- water  fossil  shells  of  species  still  living  in  the 
vicinity.  Among  the  vertebrate  remains  are  fragments  of  tusks  and  molars  of  an  elephant,  and 
molars  and  fragments  of  jaws  containing  molars  of  two  species  of  horse. 

Concerning  the  age  of  the  beds  he  conclvides  that  if  not  Quaternary,  they  can  not  be  earlier 
than  Upper  Pliocene  passing  into  Quaternary.  He  also  suggests  that  they  are  possibly  deposits 
of  King's  Lake  Shoshone,  and  not  Lake  Lahontan. 

Professor  Le  Conte  observed  that  the  level  at  this  locality  is  240  feet  higher  than  the  upper- 
most shore  line  of  the  Pleistocene  Lake  Lahontan,  which,  moreover,  did  not  extend  so  far  west 
as  Carson. 


SPURR.J  PINE    NUT    AND    SWEETWATER   RANGES.  125 

the  base  of  the  steeper  mountains.  These  hills  are  considerably 
eroded.  Near  the  mountains  the  jjebbles  are  larger,  and  in  crossing 
the  range  the  stratified  deposit  stops  at  6,000  feet  precisely,  above 
which  the  rocks  are  bare.  Below  the  uj)permost  gravels  are  benches 
in  the  detritus  and  in  the  lava  on  which  the  detritus  lies.  These 
benches,  as  well  as  the  canyon  of  the  Carson  River  at  this  point,  seem 
to  have  been  cut  during  the  recession  of  the  lake  to  which  the  gravels 
owe  their  origin,  and  whose  uppermost  shore  line  was  at  the  G,  000-foot 
cut.  On  the  western  side  of  the  range  there  is  also  a  pronounced 
scarp  above  the  6,000-foot  contour,  and  beneath  this  stratified  gravels 
constitute  the  foundation  of  the  valley  between  the  Pine  Nut  Range 
and  the  northern  end  of  the  Sweetwater  Range. 

The  uniform  and  general  distribution  of  these  water-deposited 
gravels  and  sands,  up  to  about  6,000  feet,  and  the  horizontal  groin  which 
occurs  on  the  mountains  about  the  same  height,  suggest  that  the 
deposits  were  laid  down  in  a  lake,  which  had  its  surface  at  its  time  of 
maximum  extension  at  the  altitude  above  mentioned.  That  the  lake 
was  older  than  the  Pleistocene  is  shown  b}^  the  fact  that  the  Pleisto- 
cene Lake  Lahontan  reached  an  altitude  of  only  4,375  feet.  The  indu- 
ration of  the  sediments  of  this  higher  lake,  as  seen  in  the  sandstone 
of  Carson,  also  i)oints  to  a  greater  age;  and  the  great  amount  of  sub- 
sequent erosion,  illustrated  in  the  carving  of  the  canyon  of  Carson 
River,  indicates  that  the  maximum  extent  of  the  lake  was  at  a  period 
which  was  removed  from  the  period  of  maximum  extension  of  Lake 
Lahontan  by  a  time  interval  much  longer  than  from  the  latter  x^eriod 
to  the  present  day.  On  the  whole  the  deposits  of  this  older  lake  will 
be  considered  late  Pliocene. 

SWEET\A^ATER    RANGE. 

The  Sweetwater  Range  may  be  considered  as  the  southern  prolonga- 
tion of  the  Pine  Nut  Range,  from  Avhich  it  is  separated  by  the  valley 
of  the  West  Walker  River,  at  Wellington.  It  is  also  a  spur  of  the 
Sierras,  into  which  it  passes  at  its  southern  end, 

TOPOGRAPHY. 

The  Sweetwater  Mountains  are  high  and  rugged  for  the  most  part, 
with  bold  peaks  and  cliffs.  The  eastern  face  of  the  northern  part  of 
the  range,  from  Wellington  southward  to  Desert  Creek,  is  steep  and 
straight.  Southwest  of  Wellington  the  West  Walker  River  has  cut  a 
deep  canyon  along  the  face  of  the  range,  below  the  level  of  the  broad 
desert  valley  separating  it  from  the  Pine  Nut  Range.  On  the  road 
from  Wellington  to  Sweetwater,  the  Sweetwater  Range  is  separated 
from  the  Smith  Valley  Range  on  the  east  by  the  deeply  cut  Dalzell 
Canyon. 


126  GEOLOGY    OF    NEVADA   SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

IGNEOUS   ROCKS. 
POST-PLIOCENE   BASALTIC   LAVA. 

The  gravels  and  sands  which  occur  in  the  valley  separating  the 
northern  end  of  the  Sweetwater  Range  from  the  Pine  Nut  Range 
belong  to  the  ancient  sediments  which  have  already  been  provisionally 
classified  as  Pliocene.  Along  the  canyon  of  the  West  Walker  River, 
a  short  distance  southwest  of  Wellington,  there  occur  in  places  sheets 
of  columnar  basaltic  lava,  overlying  the  gravels.  This  is  probably 
nearl}^  contemporaneous  with  the  basalt  in  Eldorado  Canyon,  of  the 
Pine  Nut  Range. 

LATE   RHYOLITIC  LAVA. 

The  highest  i)ortion  of  the  Sweetwater  Range,  just  west  of  the  post- 
office  at  SweetAvater,  is  distinguished  by  the  brilliant  light-gray,  yellow, 
and  red  which  its  rocks  assume  on  Aveathering.  These  rocks  all  seem 
to  be  gray,  essentially  fine-grained,  thin-bedded  surface  volcanics. 
They  Avere  not  examined  in  place,  but  a  typical  specimen  selected  from 
the  blocks  derived  from  this  mountain  proves  on  chemical  analysis  to 
be  A^ery  siliceous  rhyolite'^'  or  tordrillite.* 

LATE   ANDESITE   AND   LATITE. 

In  the  same  canyon  as  above  mentioned  (near  Wellington),  there 
occurs,  beneath  the  rolled  gravels,  stratified  ash,  dipping  nortliAA^est 
aAvay  from  the  mountains.  Below  this  ash  occurs  lava,  through  which 
also  the  river  has  cut.  There  are  two  distinct  flows,  the  lower  of 
Avhich  has  a  perfect  columnar  jointing,  Avhile  the  upper  one  is  often 
brecciated  and  rests  uj)on  the  apparently  eroded  surface  of  the  lower. 
The  rock  of  the  loAA^er  flow,  microscopically  examined,  proves  to  be 
bronzite-andesite,  that  of  the  upper  one  hornblende-biotite-latite. 
The  uppermost  of  these  floAvs  has  been  deepl}^  weathered,  and  has 
been  displaced  by  a  fault,  which  is  subsequent  to  the  weathering. 

The  andesite  is  of  the  same  composition  as  the  ancient  andesite 
AA'hich  forms  the  greater  part  of  the  range,  but  its  association  Avith 
breccias  and  graA^els  stamp  it  as  being  younger  than  the  main  mass 
and  intermediate  belAveen  it  and  the  latite. 

In  Dalzell  Canyon  are  coarse  volcanic  breccias,  Avith  thin  inter- 
banded  flows,  all  dipping  at  moderate  angles  irregularl3^  A  specimen 
from  a  hard  bowlder  in  the  breccia  is  hornblende-bronzite-andesite. 
These  breccias  and  thin  flows  are  probably  younger  than  the  massive 
andesite  of  the  main  range.     They  are  very  likely  of  about  the  same 

a  Dr.  H.  W.  Fairbanks  (Am.  Geol.,  Vol.  XVII,  p.  152)  mentions  a  rock  in  Ferris  Canyon,  in  the 
Sweetwater  Range,  which  is  probably  the  same  as  that  above  described. 

f>  TordriUite  is  proposed  as  the  flne-grained  equivalent  of  alaskite,  and  differs  from  rhyolite  in 
being  in  general  more  siliceous  and  containing  no  essential  feiTomagnesian  minerals.  See  J.  E. 
Spurr,  Classification  of  igneous  rocks  according  to  composition:  Am.  Geol.,  Vol.  XXV,  1900,  p.  210. 


SPURR]  SWEET WATEE    EANGE.  127 

age  as  the  breccias  in  Eldorado  Canyon,  in  the  Pine  Nut  Range, 
which  they  resemble  exactly. 

Jnst  south  of  the  post-office  at  Sweetwater  similar  hornblende- 
bronzite-audesite  comes  in,  overlying  the  ancient  rhyolite  series.  This 
is  of  the  same  general  age  as  the  breccias  in  Dalzell  Canyon. 

EARLIER   ANDESITES. 

Most  of  the  Sweetwater  Range  to  the  north  of  the  high  gray.rhyo- 
litic  peaks  above  described  is  of  red,  deejjly  eroded  lava.  Near  Well- 
ington, and  at  the  northern  end  of  Desert  Creek,  specimens  of  this 
lava  proved  on  examination  to  be  hornblende-bronzite-andesite. 

The  main  mass  of  hornblende-pja'oxene-andesite  forming  the  bulk 
of  the  Sweetwater  Range  is  older  than  the  thin  flows  and  breccias 
previously  described.  The  later  andesites  are  closely  associated  with 
gravels  which  were  chiefly  derived  from  the  erosion  of  the  earlier 
andesite. 

EARLIER  RHYOLITE. 

Just  below  Sweetwater  there  outcrops  a  gray  lava  which  has  some- 
what the  aspect  of  a  pj^roclastic  breccia.  A  specimen  proves  to  be 
rhyolite,  with  a  microcrystalline  granular  groundmass,  and  contain- 
ing small  fragments  of  a  gray  basic  lava  free  from  quartz.  This  rock 
is  of  exactly  the  same  type  as  one  examined  from  the  banded  granite- 
rhyolite  series  in  the  Pine  Nut  Range,  on  the  road  between  Genoa 
and  Wellington.  At  Sweetwater,  also,  this  lava  has  an  ancient 
appearance.  It  has  a  pronounced  jointing,  or  sheeting,  in  two  direc- 
tions, at  right  angles  to  one  another,  one  striking  N.  70°  E.  and  dip- 
ping 70°  SE.,  and  the  other  dipping  70°  NE.  This  rhyolite  is  over- 
lain by  hornblende-bronzite-andesite. 

GRANITIC   ROCKS. 

Along  the  eastern  side  of  the  northern  portion  af  the  Sweetwater 
Range,  south  of  Wellington,  there  is,  back  of  the  main  scarp,  a  second 
scarp  composed  of  gray  and  massive  rocks.  In  the  bottom  of  the 
vallej'  east  of  here  are  rolled  pebbles  and  bowlders  of  granular  and 
porphyritic  granitic  rocks.  As  one  goes  southward  from  here  he  may 
trace  the  scarp  of  gray  rocks  into  Desert  Creek  Canyon,  which  seems 
to  be  cut  in  similar  rocks,  and  the  uppermost  portion  of  Desert  Creek 
Peak  is  seen  to  be  of  the  same  material.  Just  east  of  Desert  Creek 
Peak,  at  Wileys,  granite  actually  outcrops,  beneath  hornblende- 
bronzite-andesite.  The  granite  is  in  part  coarse  and  porphyritic, 
containing  large  feldspars,  which  have  inclusions  of  dark  minerals, 
and  is  of  the  same  variety  as  noted  at  Belmont,  Ellsworth,  and  on 
the  eastern  face  of  the  Pine  Nut  Range,  southeast  from  Dayton. 
There  is  also  some  nonporphyritic  granite,  and  some  containing  few 
dark  minerals,  and  so  verging  oh  alaskite. 


128  GEOLOGY    OF    NEVADA   SOUTH    OF   40TH    PARALLEL,     [bull.208. 

The  granitic  rocks  have  been  decomposed  to  a  depth  of  many  feet, 
so  that  no  specimens  could  be  collected.  This  decomposition  occurred 
before  the  eruption  of  the  andesite,  for  this  lava  is  fresh  where  it 
overlies  the  rotten  granite.  The  period  sufficient  for  this  decomposi- 
tion is  considerable,  and  it  must  have  been  preceded  by  a  long  period 
of  erosion,  which  exposed  the  granite. 

In  the  valley  drift  above  noted  there  was  found,  besides  granite, 
specimens  of  porphyritic  siliceous  rock,  transitional  between  granite 
and  rhyolite.  It  is  possible  that  the  granite  and  the  rhyolite  at 
Sweetwater  may  be  of  nearly  the  same  age  and  may  be  correlated  with 
the  ancient  granite-rhyolite  series  of  the  Pine  Nut  Range. 

SEDIMENTARY   ROCKS. 
PLIOCENE   DEPOSITS. 

The  valley  which  separates  the  northern  end  of  the  Sweetwater 
Range  from  the  adjacent  Pine  Nut  Range  is  covered  with  bedded 
gravels,  through  which  West  Walker  River  has  cut  a  Pleistocene 
canyon.  Besides  the  rolled  gravels,  which  are  largely  derived  from 
the  andesite  of  the  mountains,  there  are  some  beds  of  stratified  ash. 
Across  the  range  from  here,  the  foot  of  the  main  scarp  north  of  Desert 
Creek  ends  in  a  sloping  lAahi  at  an  elevation  of  6,000  feet;  and  in  the 
valley  below  this  the  deposits  consist  of  rolled  gravels  similar  to 
those  exposed  in  Walker  River  Canyon. 

South  of  Dalzell  Canyon  and  east  of  the  highest  peaks  of  the  Sweet- 
water Range  is  a  broad,  gently  sloping  valley,  several  miles  across, . 
reaching  back  to  the  Sweetwater  Mountains,  which  rise  sharply  from  i 
it  at  an  altitude  of  about  7,000  feet.  The  surface  of  this  valley  is; 
smooth,  and  slight  cuts  in  it  show  a  stratified  deposit  of  arkose  and  I 
angiilar  fragments  of  lava.*^^ 

All  these  deposits  are  provisionally  referred  to  the  Pliocene. 

RESUME. 

Probably  the  oldest  rocks  of  the  range  are  a  series  of  granites  andi 
ancient  rhyolites,  which  were  perhaps  contemporaneous.  They  have 
been  jointed  by  dynamic  action,  and  are  deeply  decomposed. 

The  succeeding  geologic  formation  was  a  hornblende-pyroxene- 
andesite,  which  was  poured  out  in  great  masses  over  the  underlying 
siliceous  mountain  core.  Subsequent  to  this,  the  andesite  was  deeply 
eroded,  and  probably  a  lake  was  formed.  The  material-derived  from 
the  erosion  of  the  andesite  and  of  the  underlying  siliceous  rock  was 
spread  out  in  the  valleys  as  gravels. 

During  this  erosion  period  thin  sheets  of  andesite  similar  to  the 
main  mass  were  poured  out. 


a  See  description  of  Smith  Valley  Range,  p.  119, 


SPURR.]  SWEKTWATEK    AND    VIRGINIA    RANGES.  129 

Later  than  this,  but  also  i^robably  while  the  lak'^  still  existed,  a 
more  siliceous  lava,  which  has  been  classified  as  hornblende-latite, 
was  poured  out  in  comparatively  thin  sheets.  The  rhyolites  or  tor- 
drillites  of  the  highest  portion  of  the  range  were  probably  j)Oured  out 
at  approximately  the  same  period,  so  far  as  we  can  judge  from  the 
amount  of  erosion. 

The  shrinking  of  the  lake  exposed  to  erosion  those  lavas  which  had 
been  poured  out  in  it,  and  the  present  stream  canyons  were  cut  in  the 
lake  sediments  and  the  lavas.  At  the  same  time  thin  sheets  of 
basaltic  lava  were  locally  erupted. 

At  the  southern  end  of  the  Sweetwater  Range  there  appears  to  have 
occurred,  subsequent  to  the  retreat  of  the  lake,  a  local  ui3lift,  which 
has  elevated  the  lake  sediments  and  shore  lines  1,000  feet  above  the 
same  sediments  in  the  regions  north  of  here. 

VIRGINIA  RANGE. 

The  Virginia  Range  lies  next  east  of  the  Sierras  and  north  of  Car- 
son. It  is  ceparated  on  the  south  from  the  Pine  Nut  Range  by  a  narrow 
plateau  valle}',  in  which  Carson  River  has  cut  a  Pleistocene  canyon. 
The  range  rises  abruptly  from  the  plains  at  its  base,  and  is  high  and 
rugged.  The  northern  portion  was  examined  by  the  geologists  of  the 
Fortieth  Parallel  Survey,  and  the  geology  of  this  part  is  represented 
on  map  5  of  the  atlas  accompanying  that  rei3ort.  In  the  southern 
part  of  the  range  is  the  famous  Comstock  lode,  and  in  this  vicinity 
the  geology  has  been  studied  in  detail  by  King,  Becker,  and  others. 

IGNEOUS   ROCKS. 

With  one  or  two  nn important  exceptions,  the  Virginia  Range  is 
made  up  entirely  of  igneous  rocks.  These  were  thoroughly  studied 
by  Dr.  Becker,"  and  later  were  made  the  subjectiof  a  critical  study 
by  Messrs.  Hague  and  Iddings.^ 

The  igneous  rocks  consist  partly  of  rocks  with  porphyritic  structure 
and  fine-grained  or  glassy  groundmass,  partlj^  of  those  porphj^-itic 
rocks  whose  groundmass  is  comparativel}^  coarse,  and  x)artly  of  typical 
granular  rocks.  At  first  these  rocks  of  different  structures  but  simi- 
lar composition  were  described  as  distinct  from  one  another  and  of 
different  ages,  but  Hague  and  Iddings  considered  that  the  structures 
above  enumerated  occur  in  the  same  eruptive  bodies,  the  finer-grained 
structures  having  occurred  at  or  near  the  surface,  while  the  coarsely 
granular  ones  are  typical  of  the  core  of  the  mountain,  now  made 
accessible  by  the  deep  uiine  workings.  These  conclusions  Avere  after- 
wards contested  by  Dr.  Becker. 

a  Geology  of  the  Comstock  lode  and  the  Washoe  district:  Mon.  U.  S.  Geol.  Survey  Vol.  III. 
Also  California  Acad.  Sci.,  Bull.  0,  1886. 

bOn  the  development  of  crystallization  in  the  igneous  rocks  of  Washoe,  Nevada:  Bull.  U.  S 
Geol.  Survey  No.  17. 

Bull.  208—03 9 


130  GEOLOGY    OF    NEVADA    rfOUTH    OF    40TH    PARALLEL,     [bull. 208. 

According  to  Dr.  Becker,  the  succession  of  igneous  rocks  in  this 
district  is,  beginning  with  the  oldest: 

Granite,  metamoi^phics,  granular  diorites,  porphyritic  diorites, 
quartz-porphyry,  porphyritic  diabase,  later  diabase  (black  dike), 
earlier  hornblende-andesite,  augite-andesite,  later  hornblende-ande- 
site,  basalt. 

The  succession,  according  to  Hague  and  Iddings,  is  as  follows: 

1.  Pyroxene-hornblende-andesite    (in  its  coarser  inner  portions  becoming 

pyroxene-hornblende-diorite-porphyry    and    pyroxene-hornblende-dio- 
rite). 
Period  of  volcanic  rest  and  denudation. 

2.  Hornblende-mica-andesite. 

3.  Dacite. 

4.  Rhyolite. 

5.  Pyroxene-andesite. 

6.  Basalt. 

All  these  igneous  rocks  are  considered  by  Hague  and  Iddings  as 
Tertiarj^,  but  they  have  been  divided  into  Tertiary  and  pre-Tertiary 
by  Becker  and  others. 

SEDIMENTARY   ROCKS. 
ANCIENT   LIMESTONES. 

Mr.  Becker «  described  near  Virginia  a  small  area  of  distinctl}^ 
stratified  rocks,  consisting  of  limestones  and  greatly  metamorphosed 
micaceous  schists.  No  fossils  Avere  found.  They  are  perhaps  similar 
to  the  Triassic  limestones  found  a  few  miles  south  of  here,  in  the 
Pine  Nut  Range  near  Daj^oii.     (See  p.  207.) 

aMon.  U.  S.  Geol.  Survey  Vol.  Ill,  p.  190. 


CHAPTER   III. 
RANGES  OF  S0UTHER:N^  NEVABA. 

VIRGIN   RANGE. 

The  Virgin  Range  is  just  ^vithiu  the  eastern  limit  of  the  folded 
strata  of  the  Basin  ranges  and  west  of  the  nearlj^  horizontal  rocks  of 
the  Colorado  Plateau.**  According  to  Button,*  the  exact  boundary 
between  these  two  provinces  is  the  Grand  Wash,  the  vallej^  which 
lies  immediately  east  of  the  Virgin  Range.  In  this  valley  is  a  heavy 
fault  with  downthrow  to  the  west.     Dutton  sa^^s : 

This  fault  is  the  boiindary  of  the  G-rand  Canyon  district  and  of  the  Plateau 
country  itself.  The  region  beyond  is  a  Sierra  coimtry,  with  the  same  character- 
Lstics  as  the  Great  Basin  of  Nevada  and  western  Utah. 

SEDIMENTARY   ROCKS. 

PRE-TERTIARY. 

According  to  Marvine  ^  the  rocks  exposed  in  the  main  body  of  the 
Virgin  Range  present  the  same  general  sequence  as  is  shown  in  that 
portion  of  the  range  cut  by  the  Colorado  River.  The  fundamental 
rocks  are  Archean  gneisses,  schists,  granites,  etc.,  overlain  by  Cam- 
brian rocks,  which  in  turn  are  capped  by  a  great  thickness  of  Carbon- 

ferous  rocks  of  the  Red  Wall  and  Aubrey  groups.  At  the  extreme 
northern  end  of  the  range,  east  of  Beaver  Dam  Wash,  an  area  of  red 

andstones,  supposed  to  be  Triassic,  although  no  fossils  were  found, 
tias  been  maj)ped  bj^  the  geologists  of  the  Wheeler  Survey,^  but  is  not 
included  in  the  map  accompanying  the  present  reiDort. 

PLIOCENE. 

Besides  the  Archean  and  Paleozoic  rocks,  Marvine  *  describes  in  the 
Jrand  Wash,  which  lies  just  east  of  the  Virgin  Range,  a  series  of 
ompact  conglomerates,  which  constitute  a  very  large  amount  of  the 
t^alley  filling  and  which  have  often  been  eroded  into  a  rolling  or  hilly 
lUrface  with  deep  valleys.  This  conglomerate  contains  some  beds  of 
ava,  is  horizontally  bedded,  and  abuts  unconformably  against  the 
'olded  Carboniferous  rocks  of  the  mountains.     Southward  from  the 

aE.  E.  Howell,  U.  S.  Geog.  Surv.  W.  One  Hundredtli  Mer.,  Vol.  Ill,  p.  232. 
&  C.  E.  Dutton,  Second  Ann.  Rept.  U.  S.  Geol.  Survey,  p.  126. 
cU.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  194. 
didem.  Atlas,  geologic  sheet  No.  66. 
e  Idem,  Vol.  in,  pp.  197,  198. 

131 


132  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH    PARALLEL,    [bull.208. 

Colorado,  in  another  valley,  the  same  gravels  or  conglomerates  are  met 
with,  overlain  by  calcareous  tufas  several  hundred  feet  in  thickness. 

On  traveling  along  the  west  side  of  the  Mormon  Range  toward  the 
pass  between  it  and  the  Muddy  Range,  the  writer  noted  that  the 
greater  portion  of  the  valley  of  the  Virgin  River  lying  east  of 
the  Virgin  Range  was  covered  with  slightly  eroded  Tertiary  strata, 
probably  identical  with  the  horizontal  red,  gray,  and  brown  sand- 
stones and  conglomerates  observed  in  the  lower  portion  of  the  Meadow 
Valley  Wash/'  The  conglomerates  in  the  Grand  Wash,  on  the  other 
side  of  the  Virgin  Range,  described  by  Marvine,  probably  belong  to 
the  same  series.  As  observed  by  the  writer  in  the  Meadow  Valley 
Wash,  they  have  the  appearance  of  having  been  deposited  in  a  lake, 
although  it  is  possible  that  they  represent  the  valley  accumulation  of 
the  Colorado  River,  at  a  period  when  the  streams  of  this  system  occu- 
pied wide  valleys,  in  which  they  worked  laterall}^  and  deposited  the 
material  which  they  derived  from  the  erosion  of  the  mountains,  the 
carrying  power  of  the  streams  at  that  time  not  being  equal  to 
the  amount  of  load  received.  These  sediments  occupy  the  older  val- 
leys which  were  eroded  in  the  Paleozoic  limestones  and  in  the  earlier 
Tertiary  sediments  and  lavas,  but  they  were  laid  down  before  the 
down  cutting  of  the  latest  sharp  gorges,  for  they  stand  as  the  walls 
of  these.  They  lie  against  the  Carboniferous  limestones,  and,  as 
described  by  Marvine,  against  the  Archean  granites  along  the  Grand 
Wash. 

According  to  Dutton  ^  the  greater  part  of  the  general  denudation  of 
the  Colorado  drainage  region  was  probably  accomplished  in  Miocene 
time,  whereas  the  cutting  of  the  Grand  Canyon  probably  began  in  the 
early  part  of  the  Pliocene.  The  conglomerates  and  sandstones  under 
consideration  were  evidently  deposited  just  before  the  period  of  rapid 
canyon  cutting,  and  this,  in  conjunction  with  the  evidence  afforded 
by  the  underlying  unconformable  Tertiary  rocks  in  Meadow  Valley 
Canyon,  may  be  sufficient  grounds  for  specifying  their  age  provision- 
ally as  Pliocene. 

IGNEOUS   ROCKS. 

Marvine^  describes  large  masses  of  black  basaltic  lavas  resting 
upon  the  eastern  base  of  the  Virgin  Range.  Where  the  Colorado 
River  cuts  the  range,  at  Virgin  Canyon,  Mr.  Gilbert  '^  describes  lavas 
overlying  the  gneissic  Archean  rocks. 

STRUCTURE. 

As  seen  from  the  west,  the  limestones  of  the  central  portion  of  the 
Virgin  Range  present  dips  of  15°  to  30°,  and  strikes  indicating  some- 

a  See  p.  143. 

''  Second  Ann.  Rept.  U.  S.  Geol.  Survey,  p.  67. 

t-U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  196. 

dibid.,  p.  35. 


SPiTRR]  VIEGIN    EANGE    AND    COLORADO    CANYON.  133 

what  irregular  folding.  Marvine  "  records  that  the  main  fold  of  the 
range  is  anticlinal  and  that  a  fault  exists  along  the  east  face.  This 
is  j)robably  the  fanlt  mentioned  by  Dntton,*  which  has  a  downthrow 
to  the  west  of  between  6,000  and  7,000  feet. 

Toward  the  south  the  folding  appears  to  die  ont  so  as  to  be  nearly 
horizontal  in  the  Colorado  Canyon. 

COLORADO   CANYON. 

That  part  of  the  canyon  of  the  Colorado  which  is  represented  in  the 
sontheastern  corner  of  the  map  accompanying  this  report  lies  near 
the  boundary  between  the  Colorado  Plateau  on  the  east  and  the 
region  of  the  Desert  or  Basin  ranges  on  the  west.  The  Colorado 
Plateau  is  characterized  by  nearly  horizontal  rocks  forming  mesas  or 
benched  platforms,  while  the  region  to  the  west  has  many  different 
ranges  of  higii  rugged  mountains  composed  of  folded  strata. 

The  rocks  exposed  in  this  portion  of  the  canyon  are  Carboniferous 
and  lower.  At  the  mouth  of  the  Grand  Canyon  Mr.  Gilbert  made  a 
section  showing^  over  5,600  feet  of  rocks,  being  all  horizontal  strata 
except  the  extreme  base,  where  the  granites  and  gneisses  of  the 
Archean  appear.  Above  the  Archean  rocks  are  755  feet  of  shales, 
sandstones,  and  some  limestone  belonging  to  the  Upper  Cambrian  of 
the  Tonto  group.  Above  the  Cambrian  comes  in,  in  aptparent  con- 
formitj^,  heavy  limestones  with  some  sandstones,  having  a  thickness 
of  2,675  feet.  This  is  the  Red  Wall  limestone  of  the  Carboniferous. 
Above  the  Red  Wall  comes  in  the  Aubrey  group  of  the  Upper  Car- 
boniferous, consisting  of  1,300  feet  of  shales,  sandstones,  and  cherty 
limestones. 

Later,  Mr.  Walcotf^^  found  in  the  Grand  Canyon  a  slight  thick- 
ness of  Devonian,  rarely  over  100  feet,  between  the  Red  Wall  lime- 
stone and  the  Tonto  rocks.  Often  the  Devonian  in  this  region  is 
entirely  absent,  either  through  erosion  or  nondeposition.  The  rocks 
of  this  period  are  thin,  purplish,  fine-grained  sandstones,  becom- 
ing calcareous  and  containing  unmistakable  fossils.  Mr.  Walcott 
observed  an  erosion  break  at  the  top  of  the  Tonto  strata,  and  another 
between  the  Carboniferous  and  the  Devonian.  No  Silurian  rocks  are 
present. 

At  the  base  of  the  Tonto  there  is  a  great  unconformity,  beneath 
which  occur  sandstones,  shales,  limestones,  and  ancient  lavas  of  the 
Chuar  and  Unkar  divisions  of  the  Grand  Canyon  group  resting  upon 
thin-bedded  quartzites,  which  stand  vertical  and  are  broken  through 
bj^  intrusive  masses  of  granite.     Mr.  Walcott  considers  that  the  strata 

«U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp  194,  196. 

b  Second  Ann.  Rept.U.  S.Geol.  Survey,  p.  126;  also  Mon.  U.  S.  Geol.  Survey  Vol.  II,  atlas  PL  II. 

<^U  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  fig.  82,  p.  196. 

dAm.  Jom-.  Sci.,  3d  series,  Vol.  XXVI,  pp.  437,  484. 


134  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

between  the  Tonto  and  the  thin -bedded  qnartzites  belong  to  the  Algon- 
kian.     The  qnartzites  are  Algonkian  or  Archean." 

As  one  proceeds  down  the  Colorado  River  from  the  Grand  Canyon, 
he  finds  the  upper  strata  successively  disappearing,  until,  in  Boulder 
Canyon  and  below,  the  Archean  granites,  gneisses,  and  schists  come 
to  the  top  of  the  canyon,  except  where  covered  up  by  Tertiary  lavas. 

MORMON   RANGE. 

The  Mormon  Range  lies  immediately  east  of  Meadow  YalleJ^  It 
has  an  extent  of  about  40  miles,  and  a  north-northeast  trend.  At  its 
south  end  it  is  divided  from  the  Muddy  Range  by  the  valley  of  Muddy 
Creek,  while  at  its  northern  end  it  merges  into  irregular  volcanic 
mountains  which  cover  a  large  area  southeast  of  Pioche. 

In  topography  the  Mormon  Range  is  not  extraordinarj^,  its  peaks 
being  fairly  rugged  and  of  moderate  height.  Running  along  the 
central  part  of  the  range,  and  parallel  with  its  axis,  is  a  continuous 
notch  or  incipient  valley,  about  2,000  or  3,000  feet  deep,  which  never- 
theless has  not  yet  been  deeply  enough  eroded  to  form  part  of  the  true 
valley  system. 

SEDIMENTARY   ROCKS. 

CARBONIFEROUS. 

The  great  bulk  of  the  Mormon  Range  is  almost  free  from  igneous 
rocks  and  is  made  up  of  a  dark-blue,  sometimes  crystalline  limestone, 
with  some  reddish  shaly  beds.  In  Meadow  Valley  Canyon,  on  the 
northeast  flanks  of  the  range,  a  spur  of  this  limestone  contained  the 
following  fossils  which  were  determined  by  Dr.  Girty,  of  the  United 
States  Geological  Survey,  to  be  Upper  Carboniferous: 

Crinoid  steins.  Productns  punctatus?. 

Fenestellid.  Spirifer  cameratus. 

Fistulipora  sp.    .  Spiriferina  gonionotus. 

Productns  nebraskensis.  Seminula  mira. 
Prodnctns  splendens?. 

This  is  probably  the  Red  Wall  limestone  group  of  Gilbert's  Grand 
Canyon  section.^ 

The  same  limestone  series  is  exposed  in  Hackberry  Canyon,  a  few 
miles  south  of  here,  and  it  probablj'  constitutes  the  bulk  of  the  range. 

In  drift  from  the  southern  part  of  the  range,  found  in  the  southern 
part  of  Meadow  Vallej^  were  pebbles  containing  the  following  Upper 
Cai'bouiferous  fossils: 

Syringopora  multattennata.  Chsetetes  milleporaceus? 

Fnsnlina  cylindrica.  Prodnctns  semireticulatns. 

Archseocidaris  sp. 

Below  Hackberry   Canj^on,    in   Meadow  Valley  Canyon,  there   is 

« Fourteenth  Ann.  Rept.  U.  S.  Geol.  Survey,  pp.  505,  506,  and  507. 
b  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp.  178,  196. 


SPURB.]  MORMON    RANGE.  135 

found,  overlying  the  more  massive  dark-blue  limestone,  a  series  of 
pink  sandstones,  clierty  limestones,  and  shales  of  considerable  thick- 
ness. At  Kane  Spring,  thin-bedded,  siliceous,  cherty  limestones, 
with  yellow,  limy  shales,  belonging  to  this  upper  series,  contain  poorly 
preserved  fossils,  referre<i  by  Dr.  Girty  to  the  Upper  Carboniferous. 
This  is  undoubtedly  the  Aubrey  group  of  the  Grand  Canyon  section.'* 
The  Aubrej^  Carboniferous  lies  conformably  on  the  Red  Wall  Car- 
boniferous, and  both  lie  conformably  beneath  the  lower  rhyolite 
series  of  Meadow  Valley  Canyon.^'  They  are  separated  from  the  later 
Tertiary  formations,  especially  the  probable  Pliocene  sandstones  and 
conglomerates,  by  a  marked  unconformity. 

PLIOCENE. 

The  Pliocene  which  lies  against  the  flanks  of  the  Mormon  Range, 
in  Meadow  Valley  Canyon,  will  be  considered  in  the  special  descrip- 
tion of  the  canyon.  The  rocks  consist  of  horizontal  or  slightly  undu- 
lating red,  gray,  and  brown  sandstones  and  conglomerates,  the  latter 
often  honeycombed,  rising  to  a  height  of  about  5,500  feet  above  sea 
level,  and  lying  against  the  folded  limestones  of  the  mountains.  The 
conglomerates  contain  pebbles  of  the  fossiliferous  Carboniferous 
limestones,  as  well  as  of  the  older  Tertiary  formations. 

As  seen  from  the  gap  between  the  Mormon  Range  and  the  Muddy 
Range,  large  areas  on  the  eastern  side  of  the  Mormon  Range  are 
probably  occupied  by  Pliocene  strata  similar  to  those  found  on  the 
western,  these  beds  covering  much  of  the  broad  valley  between  the 
Mormon  Range  and  the  Virgin  Range. 

IGNEOUS   ROCKS. 

Despite  the  fact  that  much  volcanic  material  was  found  closely 
adjacent  to  the  Mormon  Range  on  the  north  and  west,  there  seems  to 
be  little  in  the  range  itself.  The  volcanic  rocks  on  its  western  flanks 
will  be  treated  in  the  description  of  Meadow  Vallej^  Canyon. 

STRUCTURE. 

The  Mormon  Range,  as  viewed  from  the  west,  appears  to  consist 
chiefly  of  an  anticlinal  fold,  whose  trend  diverges  somewhat  from 
that  of  the  range,  since  it  runs  in  a  direction  west  of  north,  while  that 
of  the  range  runs  east  of  north.  On  the  western  slope  of  the  range 
there  was  observed  a  parallel  synclinal  fold  of  comparatively  small 
extent,  flanked  by  another  slight  anticline  still  farther  west.  These 
two  folds  are  probably  local.  They  are  succeeded  on  the  west  by  a 
syncline  Avhich  occupies  the  broad  plateau  valley  in  which  Meadow 
Vallej^  Canj'on  lies.     (See  fig.  10.) 

As  seen  from  the  north  the  maiii  anticline  is  comparatively  gentle, 

a  Gilbert,  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp.  177,  196. 
b  See  description  of  Meadow  Valley  Canyon,  p.  140. 


136  GEOLOGY    OF    NEVADA   SOUTH    OF    lOTH    PARALLEL,     [bull. 208. 


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the  clips  on  both  sides  appearing  to  be 
about  15°.  Farther  south,  however, 
these  dips  gradually  increase,  and  in 
one  conspicuous  peak  in  the  south- 
central  part  of  the  range  the  strata  are 
sharply  compressed,  forming  a  type  of 
structure  quite  unusual  in  the  desert 
ranges,  but  still  present,  especially  in 
certain  ranges  Ij'ing  closelj^  east  of  the 
Sierra  Nevada.'' 

It  has  already  been  noted  that  the 
limestone  which  forms  the  Mormon 
Range  seems  to  be  conf ormabl}^  over- 
lain, on  the  flanks  of  the  range,  by  a 
Tertiarj^  rhyolite  and  rhyolite  tuff 
series.*  That  there  was  an  erosion 
interval  between  the  Carboniferous  and 
the  rhyolite  period  is  shown  by  the 
irregularity  of  the  contact,  as,  for  ex- 
ample, at  the  mouth  of  Hackberry 
Canyon,  where  the  rhyolite  is  found 
on  one  side  of  the  canyon  and  not  on 
the  other.  Nevertheless,  most  of  the 
folding  which  brought  about  the  forma- 
tion of  the  range  certainlj^  did  not  begin 
until  after  the  rhyolite  period.  The 
limestones  must  also  have  taken  j)art 
in  later  movements,  evidenced  by  fold- 
ing in  the  postrhj^olitic  Tertiary  rocks 
to  be  described  in  considering  Meadow 
Valley  Canyon,  which  are  separated 
from  the  rhyolites  by  an  unconformity. 
Thus  the  total  amount  of  folding  in  the 
range  is  the  combined  result  of  all  the 
Tertiary  movements,  which,  from  phe- 
nomena observed  in  Meadow  Valley  Can- 
yon, seem  to  be  still  in  progress. 

MUDDY  RANGE. 

The  Muddy  Range  is  a  soutliAvard  con- 
tinuation of  the  Mormon  Range,  being 
separated  from  it  only  by  the  gap  of 
Muddy  Creek.  It  extends  south  to  the 
Colorado  River,  where  it  is  separated 
from  the  Colorado  Range  hy  Boulder 
Canyon. 


"C.  D.  Walcott:  Am.  Jour.  Sci.,  .M  series,  Vol.  XLIX,  189.5,  p.  169. 
(fSee  description  of  Meadow  Valley  Canyon,  p.  140. 


SPUKR.]  MUDDY    RANGE.  137 

SEDIMENTARY   ROCKS. 

The  Carboniferous  strata  of  tlie  Mormon  Rani>e  appear  in  tlie  field 
to  be  continuous  into  the  northern  end  of  the  Muddy  Range.  The 
soutliern  portion  of  the  range,  however,  is  represented  on  the  Wlieeler 
survey  geologic  map  as  composed  of  Triassic  rocks." 

At  the  extreme  southern  end  of  the  range,  in  Boulder  Canj^on,  only 
the  Archean  igneous  rocks  and  gneisses  are  exposed,  as  described  by 
Mr.  Gilbert.*     These  are  overlain  by  Tertiary-  lavas. 

The  following  observations  were  made  b}^  Mr.  R.  B.  Rowe'^: 

CARBONIFEROUS. 

About  4  miles  west  of  Logan,  on  Muddj"  Creek,  there  occurs  prob- 
ably Carboniferous  limestone,  overlying  Mesozoic  sandstones  and 
conglomerates.  Between  Logan  and  Weiser's  ranch,  above  the  Nar- 
rows, Paleozoic  limestone  is  again  shown,  being  brought  against  the 
Mesozoic  by  a  heavy  fault.  The  Mesozoic  also  seems  to  lie  conform- 
ably upon  the  limestone  on  one  side  of  the  fault  plane. 

Fossils  collected  3  miles  west  of  Logan  post-office  by  Mr.  Rowe 
were  determined  by  Dr.  Girty  a"s  rather  doubtfull}^  Permian. 

MESOZOIC. 

At  the  first  locality  above-mentioned,  4  miles  west  of  Logan  j)Ost- 
office,  there  are  bright-red  hills  of  massive  cross-bedded  sandstone 
showing  no  bedding  iDlanes.  West  of  these  hills  are  softer  red-clay 
beds,  bluish  shale  beds,  gray  conglomerates,  and  thin  limestone  beds. 
Some  of  the  limestone  beds  contain  fossils,  regarded  by  Mr.  Rowe  as 
Jurassic.  Mr.  Rowe's  collection  was  examined  by  Mr.  T.  W.  Stan- 
ton, who  referred  it  possiblj^  to  the  same  horizon  as  fossils  from  simi- 
lar beds  in  the  south  part  of  the  Spring  Mountain  Range.  He  believes 
the  horizon  is  not  younger  than  the  Triassic  and  may  be  as  old  as  the 
Permian,  but  as  the  forms  are  all  new  no  definite  statement  can  be 
made. 

One  of  the  conglomeratic  strata  contains  considerable  petrified 
wood.  From  some  of  the  darker  shales  of  the  Mesozoic  some  narrow 
seams  of  coal,  from  one-half  to  one  inch  in  thickness,  have  been 
reported. 

At  the  second  localitj^  mentioned  above,  between  Logan  and 
Weiser's  ranch,  the  Mesozoic  again  appears,  lying  conformably  upon 
the  limestone.^ 

TERTIARY. 

On  the  north  side  of  Muddy  Creek,  above  the  old  California  cross- 
ing, are  the  red,  j^ellow,  and  bluish  deposits  of  the  Tertiary.     On  the 


nU,  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Atlas  Sheet  No.  66. 

h  Idem,  Vol.  Ill,  p.  a5. 

(■Taken  from  his  notebooks  after  Mr.  Rowe's  death,  by  the  writer. 

f'  This  Mesozoic  is  mapped  as  Triassic  to  conform  with  the  Wheeler  survey  mapping  in  the 
southern  part  of  the  I'ange.  It  will  be  ob.3erved,  however,  that  these  beds  may  be,  in  part  at 
least,  the  same  as  those  mapped  in  the  Spring  Mountain  range  as  Jurassic. 


138 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


south  side,  and  iindoubtedl}^  connected  with  these,  are  clay  deposits 
of  considerable  thickness  and  extent. 

Between  Logan  and  Weiser's  ranch  red  and  yellow  clays  and  ancient 
talus  deposits,  now  hardening  into  conglomerates,  lie  un conformably 
upon  the  Mesozoic. 

IGNEOUS   ROCKS. 

In  the  northern  part  of  the  range  the  writer*  observed  volcanic  rocks 
overlying  the  folded  strata.  On  the  Wheeler  maps  patches  of  basalt 
are  shown  in  a  similar  relation  in  the  southern  part  of  the  range,  and 
these  extend,  as  described  by  Mr.  Gilbert,  to  Boulder  Canyon. 

STRUCTURE. 

At  the  northern  end  of  the  range  the  stratified  rocks  seemed  from 
a  distance  to  dip  eastward  at  high  angles,  but  the  actual  structure  w^as 
not  made  out.  The  folding  probablj^  decreases  rapidly  toward  the 
south. 

The  following  observations  were  made  by  Mr.  R.  B.  Rowe : 
About  4  miles  west  of  Logan  there  is  probably  a  fault  between 
the  Paleozoic  and  the  Mesozoic.     The  Mesozoic  dips  quite  sharply  to 


13  2  ■* 

Fig.  11.— Cross  section  of  Muddy  Range,  after  R.  B.  Rowe. 

1.  Carboniferous  limestone.  3.  Mesozoic  conglomerates,  shales,  and  limestones. 

2.  Massive  i-ed  Mesozoic  sandstone.        4.  Tertiary  clays  and  consolidated  talus  deposits. 

the  west.  Between  Logan  and  Weiser's  ranch  the  fault  is  beautifullj^ 
shown,  bringing  the  Mesozoic  against  the  Paleozoic  limestones.  On 
the  west  side  of  the  range  the  Mesozoic  seems  to  line  conformably 
upon  the  limestone.  The  dip  of  the  limestone  is  almost  perpendicu- 
lar, while  the  Mesozoic  lies  against  it,  with  a  much  lower  dip,  on  the 
east  side.     (See  fig.  11.) 

COLORADO   RANGE. 


The  Colorado  Range  is  a  southward  continuation  of  the  Muddj^ 
Range,  and  is  separated  from  it  by  the  Colorado  River  at  Boulder 
Canyon.     Its  geology  is  represented  on  the  Wheeler  geologic  atlas 


aJ.  E.  S. 


SPURR.]  RANGES    OF    SOUTHERN    NEVADA.  139 

(slieet  No.  66)  as  consisting  essentiallj^  of  an  Arcliean  core  overlain 
by  lavas  and  flanked  }:>y  Pleistocene  detritns. 

ELDORADO   RANGE. 

The  Eldorado  Range  lies  west  of  the  Colorado  Range,  being  separated 
from  it  by  the  Colorado  River.  As  represented  on  the  Wheeler  atlas, 
its  geology  is  abont  the  same  as  that  of  the  Colorado  Range. 

MEADOW  VALLEY  CANYON. 
TOPOGRAPHY. 

Meadow  Valley  Canyon  is  cut  in  the  bottom  of  a  broad  north-south 
plateau  vallej",  which  separates  the  Meadow  Valley  Range  on  the  west 
from  the  Mormon  Range  and  other  mountains  on  the  east.  Although 
the  canyon  is  dry  for  long  stretches,  yet  such  water  as  may  flow  in  it 
is  carried  to  the  Colorado,  of  whose  drainage  the  canyon  forms  a  part. 
That  portion  of  the  valley  which  is  here  described  is  about  90  miles 
in  length,  extending  from  the  vicinity  of  Pioche  soutliward  to  West 
Point  or  Moapa.  The  canyon  begins  a  short  distance  south  of  Pioche, 
and  grows  continually  deeper  toward  the  south.  The  continuation  of 
Meadow  Valley  northward  from  Pioche  is  called  Duck  Vallej^,  which 
is  a  tj-pical  broad  desert  valley  with  no  canyon.  Opposite  Pioche 
the  appearance  is  already  unlike  that  of  the  tj^pical  desert  vallej"  of 
the  region.  There  comes  in  a  central  narrow  strip  of  level  wash, 
marking  the  channel  of  drainage,  while  on  both  sides  there  rises  to 
the  mountains  a  detrital  slope,  which,  unlike  that  of  most  Nevada 
valleys,  is  cut  up  into  low  hills.  To  the  south  the  central  drainage 
channel  becomes  deeper,  the  slopes  sharper,  and  the  hills  more  cut  up. 
To  the  north  the  reverse  is  the  case,  until  the  valley  appears  almost 
flat,  like  the  typical  Nevada  valley. 

From  the  vicinity  of  Pioche  the  incision  of  the  drainage  into  the 
valley  bottom  becomes  progressively  more  pronounced  southward, 
until  some  few  miles  south  of  Panaea  a  box  canyon  begins,  which 
soon  attains  a  depth  of  500  feet,  and,  within  a  few  miles,  1,000  or 
1,500  feet  (PL  VI,  A).  Some  miles  south  of  here,  at  Kernan's  ranch, 
the  canyon  walls  are  estimated  to  be  fully  2, 000  feet  high.  Still  farther 
south,  and  just  northeast  of  the  Mormon  Range,  the  valley  widens  out 
into  a  broad  basin  inclosed  by  mountains,  for  a  few  miles  below  which 
another  shorter  and  somewhat  lower  canj^on  is  entered.  Below  this 
is  a  broad,  gently  sloping  plateau- valley,  in  which  the  drainage  chan- 
nel, though  generally  sharp,  is  shallow.  This  plateau  gi'ows  wider 
toward  the  south,  as  also  the  vallej^  which  is  cut  in  it.  At  the  junction 
of  the  Muddj^  Creek  and  Meadow  Creek  drainage,  near  West  Point  or 
Moapa,  the  valley  is  2  miles  wide. 

Meadow  Vallej^  Canj'on  ofl"ers  exceptional  advantages  for  study. 
Most  of  the  Nevada  deserts  are  nearly  level,  and  appear  to  be  filled 
with  Pleistocene  accumulations,  mostly  subaerial.     Observations  in 


140  GEOLOGY    OF    NEVAIVA   SOUTH    OF    40TH    PARALLEL,     [bull.208 

some  of  these  flat  valleys,  however,  show  that  Tertiary  rocks  crop  out  in 
patches  and  that  the  Pleistocene  cover  is  onlj^  a  veneer.  But,  tliere 
being  no  drainage,  in  these  valleys,  there  is  very  rarely  an  opportunity 
to  find  sections  cut  by  running  waters,  so  as  to  study  the  real  valley 
filling.  In  Meadow  Creek  Canyon  we  have  such  an  opportunity. 
The  slight  incision  in  the  valley  opposite  Pioche  grows  to  a  continuous 
canyon  1,000  or  2,000  feet  deep,  whose  walls  afford  excellent  sections 
of  the  Tertiary  sediments  and  lavas  which  constitute  the  real  valley 
filling  between  the  ranges  of  Paleozoic  strata  on  either  side. 

PALEOZOIC    ROCKS. 

On  the  west  of  the  valley,  the  Highland  and  Meadow  Valley  ranges, 
and  on  the  east  the  Mormon  Range,  are  composed  of  Paleozoic  strata, 
the  Highland  Range  being  chiefly  Cambrian,  the  rest  largely  Carbon- 
iferous. Between  these  mountain  ranges  the  valley  probably  existed 
before  the  deposition  of  any  of  the  Tertiarj^  rocks. 

RHYOLITE. 

The  oldest  of  the  post-Paleozoic  rocks  noted  in  Meadow  Valley  Can- 
yon was  j-hj^olite.  This  Avas  flrst  encountered  at  the  ui)per  end  of  the 
canyon,  near  Yokum's  ranch,  where  it  occurs  in  rugged  outcrops.  A 
specimen  proved  to  be  a  siliceous  biotite-rhyolite.  This  has  been 
eroded,  and  against  it  has  been  laid  down  a  horizontally  stratified 
white  rhyolite  sandstone  derived  from  it.  The  sandstone  is  hardened 
and  forms  cliffs  and  buttes.     The  rhyolite  is  thoroughly  decomposed. 

South  of  here,  the  basal  rhyolite  may  be  traced  for  some  short  dis- 
tance in  the  canyon  walls  till  it  sinks  below  the  bottom  of  the 
canyon  and  gives  place  to  an  enormous  series  of  the  overlying  rhyolite 
sandstones,  which  contain  interbeclded  thin  sheets  of  rhj^olite.  There 
are  in  many  places  evidences  that  the  basal  rhyolite  was  eroded  before 
the  deposition  of  the  overlying  detrital  series,  for  the  latter  often  rests 
in  the  irregularities  of  the  surface  offered  bj^  the  former.  The  rhj^o- 
lites  and  the  overljang  derived  sediments  are  folded  throughout  (dip- 
ping exceptionally  as  much  as  30°,  though  usually  deviating  only 
slightly  from  the  horizontal),  and  are  often  faulted,  small  faults 
being  numerous,  and  those  of  KX)  feet  or  more  being  not  infrequent. 

The  basal  massive  rhj^olite  was  again  observed  at  Hackberry  Can- 
yon. In  the  section  afforded  here  the  lowest  member  is  a  white  bio- 
tite-rhyolite, thoroughly  decomposed.  At  the  mouth  of  the  canyon 
this  rhyolite  overlies  the  Carboniferous  limestones  conformably',  the 
whole  being  folded  together  and  unconformable  to  the  overlying  for- 
mations. 

RHYOLITE-SANDSTONE    SERIES. 

At  the  upper  end  of  Meadow  Valley  Canyon,  at  Yokum's,  the  con- 
solidated rhyolite  sandstone  and  conglomerate  whicli  overlies  the 
massive  rhyolite  has  alreadj^  been  described,  and  also  its  occurrence 
in  the  canyon  immediately^  to  the  south,  where  it  succeeds  the  basal 


U.    S.    GEOLOGICAL  SURVE 


ULLETIN   NO.    20S       PL.    VI 


A.      RHYOLITE   WALLS   OF    MEADOW    VALLEY    CANYON    AT    CARSON'S    RANCH. 


B.      PLIOCENE  CONGLOWIERATE    IN    MEADOW   VALLEY   CANYON    AT   CANE  SPRING. 


SPURK.] 


MEADOW    VALLEY    CANYON. 


141 


lava  above  an  apparent  erosion  gap  and  is  folded  with  it.  The 
rhj'olite-saudstone  or  tnff  series  is  overlain  unconformably  by  ande- 
site,  and  is  also  cut  by  thin  intrusive  sheets  of  it. 

There  appears  also  to  have  been  considerable  disturbance  even 
during  the  deposition  of  the  rhyolite-sandstone  or  tuff  series,  which 
is  expressed  by  slight  erosion  gaps  and  irregularities  between  adjoin- 
ing beds.  During  the  deposition  of  this  series,  therefore,  periodic 
effusion  of  thin  sheets  of  lava  and  erosion  seem  to  have  gone  on 
simultaneousl3^  Some  of  the  thin  rhyolite  sheets  rest  one  upon 
another  with  diverging  angles  of  banding,  indicating  to  the  observer 


Fig.  12.— Sketch  section  of  east  wall  of  Meadow  Valley  Canyon  just  south  of  Carson's  ranch, 
showing  unconformity  between  rhyolite  sands  and  overlying  dacitic  lavas. 

at  first  sight  an  unconformity,  since  they  have  the  appearance  of 
being  white  stratified  rock. 

This  series  was  estimated  to  be  4,000  feet  thick,  and  is  exposed 
soutliAS'ard  to  a  point  about  45  miles  south  of  Pioche,  where  it  gives 
place,  on  account  of  the  general  southerl}^  di]3  of  the  folded  beds,  to 
later  overlying  sediments  and  lavas. 


ANDESITE-LATITE    SERIES. 

There  is  found,  overlying  the  rhyolite-sandstone  or  tuff  series,  at 
Yokum's  ranch  and  in  the  canj^on  to  the  south,  several  hundred  feet 
of  basic  lava,  specimens 
which  proved  to  be  in  gen- 
eral bronzite-biotite-ande- 
site.  A  specimen  coUecte;! 
just  above  Yokum's,  prob- 
ably from  the  same  gen- 
eral series,  is  biotite-horn- 
blende-C[uartz-latite. 

This    andesite-latite    se- 
ries  rests    unconformably 
upon  the  basal  rhyolite  or  on  the  overlying  rhyolite  tuff  (fig.  12)  and 
also  intrudes  them  in  thin  intercalated  sills  (fig.  13). 

From  the  northern  end  of  the  canyon  the  andesites  were  not 
observed  for  many  miles  southward,  but  in  Hackberry  Canyon  they 
were  again  found  exposed  in  exceptionally  good  section.  Here  they 
overlie  the  basal  rhyolite  unconformably,  and  are  themselves  tilted  so 
as  to  be  unconformable  below  the  overlying  sands  and  gravels.     At 


Fig.  13. — Sketch  section  of  west  wall  of  Meadow  Val- 
ley Canyon  at  same  locality  as  flg.  12,  showing 
intrusion  of  overlying  sheet  of  dacitic  lava  into 
underlying  rhyolite  sands. 


142 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 


this  point,  as  also  at  the  northern  end  of  Meadow  Valley  Canyon,  the 
andesite  contains  considerable  masses  of  volcanic  breccia.  It  is  con- 
sidex'ably  decomposed,  though  not  so  much  as  the  underlying  rhyolite, 
and  specimens  proved  to  be  pyroxene-andesite. 

REDDISH   DACITES   AND    RHYOLITES   AND    ASSOCIATED    SEDIMENTS. 

In  the  southern  half  of  the  northern  portion  of  Meadow  Valley 
Canyon,  above  the  open  basin  to  the  northeast  of  the  Mormon  Range, 
the  andesites  were  not  observed;  but  the  rhyolite  sandstone  or  tuff 
formation  was  found  to  be  overlain  by  beds  of  brown  and  yellow  tuff, 
containing  a  variable  amount  of  red  lava,  in  the  form  of  sheets.  The 
great  variability  in  thickness  of  the  lava  sheets,  and,  therefore,  of  the 
interbedded  sandstones,  makes  a  study  of  the  series  very  difficult,  no 
two  sides  of  the  canyon  ever  matching;  but,  so  far  as  examined,  the 


Scale 


Fig.  14. — Sketch  of  east  side  of  Meadow  Valley  Canyon  near  locality  of  figs.  12  and  13,  showing 
contact  of  imderlying  rhyolite  and  overlying  dacite,  with  no  rhyolite  sands  between. 

volcanic  rocks  found  in  this  upper  reddish  series  are  in  part  biotite- 
hornblende-dacite  and  in  part  pink  rhyolite.  It  is  not  plain  in  the 
field  whether  this  series  of  dacites  and  reddish  rhyolites  is  older  or 
younger  than  the  andesites,  for  the  two  are  not  found  together;  but 
from  the  fact  that  the  andesite  is  often  found  resting  directly  upon 
the  basal  rhyolite,  it  is  inferred  that  it  is  probably  older  than  the 
reddish  dacite-rhyolite  series.  Between  the  series  of  red  lavas  and 
yellow-brown  tuffs  and  the  underlying  series  of  white  rhj^olites  and 
white  tuffs  there  is  a  marked  unconformity  and  erosion  gap  (fig.  14). 
The  dacites  and  reddish  rhyolites  not  only  form  interbedded  sheets 
contemporaneous  with  the  yellow-brown  tuffs,  and  furnish  many 
of  the  pebbles  in  the  associated  gravels,  but  they  have  cut  the  same 
gravels  and  tuffs  as  intrusive  sills,  which  are  often  of  considerable 
thickness.  Thus  there  are  exposed  sections  in  the  canyon  walls  with 
the  reddish  volcanics  at  the  base  and  the  j^ellow-brown  tuffs  above, 
giving  a  false  appearance,  as  if  the  sediments  were  younger  than  the 
lava. 


SPTTRE]  MEADOW    VALLEY    CANYOJSI.  143 

At  one  locality,  near  Kernan's  ranch,  the  brown  tuffs  and  red  lavas 
were  seen  to  be  overlain  bj^  a  flow  of  pyroxene-olivine-basalt,  whose 
lower  boundary  is  irregular. 

This  whole  series  of  red  lavas  and  brown  tuffs  is  broadly  folded, 
although  not  so  much  as  the  rhyolitic  series  below.  It  has  in  general 
a  southerly  dip,  and  where  the  canj^on  gives  way  below  Kernan's  ranch 
to  the  broad,  level  basin  which  lies  northeast  of  the  Mormon  Range 
it  is  overlain  unconformably  by  horizontal  brown  sandstone  or  tuff 
belonging  to  a  later  epoch. 

PLIOCENE   BEDS. 

In  the  valley  near  Panaca  the  stream  bottom  has  on  both  sides 
scarps  60  to  100  feet  high,  consisting  of  horizon tallj^  stratified  silt  and 
sand.  These  sediments  are  sometimes  green  and  yellow  and  pass  into 
rhyolitic  arkose.  The  scarps  are  cut  down  in  a  level  valley  plateau 
which  has  an  elevation  of  about  5,000  feet;  and  from  here  on  both 
sides  a  succession  of  benches,  more  or  less  dissected,  rise  to  the  moun- 
tains.    The  highest  well-marked  bench  was  estimated  at  6,000  feet. 

In  the  northern  portion  of  Meadow  Valley  Canyon,  between  Carson's 
and  Kernan's  ranches,  tlie  different  series  of  interbedded  lavas  and 
tuffs  above  described,  which  are  all  more  or  less  folded,  give  way  for 
a  few  miles  on  the  west  side  of  the  valley  to  a  deposit  of  about  2,000 
feet  of  clean,  brown  volcanic  sandstone  and  tuff,  beautifully  stratified 
horizontally,  and  extending  to  the  top  of  the  hills.  The  deposits  are 
unfolded  and  unbroken,  dipping  south  about  2°,  and  having  a  maxi- 
mum elevation  of  about  5,500  feet.  In  the  upper  part  of  this  sand- 
stone series  there  seems  to  be  a  few  sheets  of  rhyolite  and  basalt,  the 
basalt  being  the  younger. 

South  of  Kernan's  ranch  a  series  of  brown,  horizontally  stratified, 
volcanic  sandstones  or  tuffs  comes  in  uncomformably  above  the 
slightly  folded  red  lava  and  brown  tuff  series,  and  fills  the  broad  basin 
which  lies  northeast  of  the  Mormon  Range.  Of  these  horizontal  sand- 
stones there  is  shown  in  the  bottom  of  the  valley  a  thickness  of  about 
800  or  900  feet,  although  neither  the  bottom  nor  the  top  was  seen. 
Below  the  sandstones  are  barely  exi)osed  horizontal  conglomerates, 
well  indurated,  and  containing  pebbles  of  various  sizes  up  to  2  feet  in 
diameter.  This  sandstone  series  continues  south,  and  lies  up  against 
the  slopes  of  the  Mormon  Range  to  a  height  of  about  2,000  feet  above 
the  valley  or  about  5,500  feet  above  sea  level.  The  lower  portions  of 
the  sandstone  are  indurated,  while  the  upper  parts  are  softer.  They 
are  often  honeycombed  i;i  consequence  of  unequal  consolidation  and 
erosion.  In  one  locality  they  are  overlain  by  a  sheet  of  very  recent 
tordrillite.  These  horizontal  rocks  acquire  a  slight  wavy  structure 
on  approaching  the  spur  of  Paleozoic  limestones  which  constitutes 
the  southern  barrier  of  the  basin.  There  are  developed  gentle  folds 
with  axes  parallel  to  the  spur,  and  dijjs  averaging  not  more  than  10°. 


144 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 


Close  up  to  the  limestone  buttress  the  folding  is  somewhat  closer, 
and  the  strata  have  a  wrinkled  appearance. 

At  Hackberry  Canyon  the  same  series  of  horizontally  stratified  con- 
glomerates and  soft  sandstones  overlies  the  pyroxene-andesite,  from 


Fig.  15. — Sketch  section  of  south  wall  of  Hackberry  Canyon  near  junction  with  Meadow  Valley 
Canyon,  showing  Pleistocene  faiilts  and  simple  fault  scarps. 

1.  Carboniferous  limestone. 

2.  Rhyolite  and  derived  sediments  (probably  early  Tertiary). 

3.  Consolidated  honeycombed  conglomerate  and  sandstone  (probably  Pliocene). 

4.  Pleistocene  faults. 

which  it  is  separated  by  an  unconformity  and  an  erosion  gap.  At  the 
mouth  of  Hackberry  Canyon  the  same  series  is  found,  honeycombed 
and  overlying  unconforiiiably  the  upturned  basal  rhyolites.  Both  the 
horizontal  conglomerates  and  sandstones  and  the  underlying  rocks 


2  4  1 

Fig.  16.— Sketch  section  of  north  wall  of  Meadow  Valley  Canyon,  3  miles  southwest  of  mouth  oJ 
Hackberry  Canyon,  showing  a  pre-Pliocene  fault. 

1.  Interbedded  pink  and  yellow  sandstones,  sandstone  shales,  and 

bluish-green  siliceous  limestones. 

2.  Homogeneous  thin-bedded  siliceous  limestones  (Carboniferous). 

3.  Pliocene  (?)  conglomerate. 

4.  Pre-Pliocene  fault. 

have  been  displaced  by  recent  faults,  which  are  directly  expressed  ii 
the  topography  (fig.  15).  Farther  south,  a  short  distance  down  th( 
main  Meadow  Valley  Canyon  (or,  as  it  is  called  at  this  point,  Mormor 
Canyon),  the  liorizontal    conglomerate  overlies   unconformably  th( 


SPUKR.] 


MEADOW    VALLEY    CA^YON. 


145 


Paleozoic  limestones  and  sand- 
stones. At  this  point  a  fault  lias 
displaced  the  Paleozoic  rocks,  but 
not  the  overlying  conglomerates, 
showing  that  it  occurred  before  the 
deposition  of  the  latter  (fig.  16).  A 
short  distance  south  of  here  the 
horizontal  sandstone  is  brought  to 
the  bottom  of  the  canyon  by  the 
dipping  down  of  the  contact  be- 
tween it  and  the  lower  formations, 
and  from  liere  to  the  neighborhood 
of  Moapa  or  West  Point  it  is  the 
principal  formation  exi^osed  in  the 
valley,  the  older  Tertiary  deposits 
not  being  observed  and  the  Pale- 
ozoic rocks  only  in  patches. 

Froui  Kane  Spring  southward  to 
Grapevine  Spring,  a  distance  of 
about  3  miles,  there  is  a  ver}^  inter- 
esting section  (fig.  17).  Above  the 
upturned  and  eroded  Paleozoic 
limestones  occur  the  consolidated 
brownish  sandstones,  grits,  and 
conglomerates  of  the  horizontal  se- 
ries. The  conglomerates  contain 
pebbles  of  limestone,  chert,  and 
quartz  from  the  Paleozoic  series, 
white  rhyolite  from  the  basal  rhyo- 
lite  series,  and  characteristic  red 
lava  from  the  dacite-rhyolite  series 
(PI.  VI,  B).  There  has  been  a  slight 
local  folding  of  the  brown  sand- 
stones and  conglomerates,  Avhich 
seems  to  have  been  partly  caused 
by  the  advent  of  a  considerable 
sheet  of  rhyolite.  This  rhyolite 
overlies  the  sandstones  and  has 
also  cut  into  them  as  sills.  Prob 
ably,  however,  part  of  the  fold, 
iug  took  place  before  the  intru- 
sion. At  Grapevine  Spring  there 
has  been  a  late  faulting  which  has 
disj^laced  the  lava  as  well  as  the 
sandstones,  and  here  also  the  up- 
turning of    the    strata    has    been 


^  w  a 


£  -g.  O 


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Jg 


'ftj'Vot'-"*' 


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V    tir  I 


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Bull.  208—03- 


-10 


1-^6 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


greatest,  resulting  in  a  local  dip  of  as  much  as  45°.  Lying  upon 
the  uj)turned  edges  of  the  brown  sandstones  here,  and  also  upon  the 
later  rhj^olite,  is  a  series  of  consolidated  grits  and  conglomerates, 
distinguished  bj^  a  gray  color  as  opposed  to  the  reddish  and  brown 
colors  of  the  beds  below  (fig.  18).  Southward  from  GraiDevine  Spring 
to  Moapa,  the  horizontal  gray  sandstone  and  conglomerate  is  contin- 
ually observed  overlying  the  red  and  yellow  series,  which  is  again 
horizontal  and  mostly  conformaljle  to  it. 

The  very  slight  folding  of  all  the  beds  which  have  been  described 
under  the  last  head  separates  them  from  all  the  underlying  uncon- 
formable Tertiary  series.  Their  position,  structure,  and  distribution 
show  that  they  are  probably  lake  beds,  and,  indeed,  they  lie,  partly 


Scale 


4ofeet 


Fig.  18. — Sketch  section  of  west  wall  of  Meadow  Valley  Canyon  at  Grapevine  Spring,  Enlarged: 
from  fig.  17.    Showing  fault  gullies  in  Pliocene  rocks. 

at    least,    in    inclosed   rock   basins.     These   beds   are   provisionally 
referred  to  the  Pliocene. « 

PLIOCENE   RHYOLITES. 

In  the  section   between   Kane    Spring   and  Grapevine  Spring  the  ^ 
moderately  tliick  sheet  of  rhyolite  above  noted  is  of  an  age  intermedi- 
ate between  the  lower  brown  Pliocene  sandstone  series  and  the  upj)er 
gray  Pliocene  series,  since  it  overlies  the  one  and  underlies  the  other. 
It  is  a  glassy  rock,  and  veiy  little  can  be  told  of  its  composition. 

PLEISTOCENE    RHYOLITE   AND    BASALT. 


At  several  points  very  recent  lavas  are  seen,  which  form  the  latest 
phase  of  volcanic  activity  in  this  region.  In  the  canyon  near  the 
northern  end  of  the  broad  basin  which  lies  northeast  of  the  Mormon 
Range  the  topmost  rock  at  one  i^oint  was  found  to  be  a  sheet  of 


"See  description  of  Virgin  and  Mormon  ranges,  pp.  131  and  lo.'). 


SPURR.] 


MEADOW    VALLEY    CANYON. 


147 


pyroxene-olivine-basalt,  overlying  with  an  irregular  contact  strati- 
tied  volcanic  sand  aiaparently  belonging  to  tlie  dacite-red  rhyolite 
period. 

Near  the  southern  end  of  the  same  basin  a  thin  sheet  of  glassy  tor- 
drillite  comes  down  into  the  valley,  covering  the  hills  in  such  a  way 
as  to  show  that  the  present  topograj)liy  was  developed  before  the  lava 
effusion. 

At  Hackberr^^  Canj'on  thin  sheets  of  glassy  lava  overlie  the  hori- 
zontal Pliocene  sandstones  and  conglomerates.  Specimens  of  these 
sheets,  taken  at  different  but  neighboring  points,  proved  to  lie  tor- 
drillite  and  pyroxene-olivine-basalt.  The  two  seem  to  be  practically 
contemporaneous,  and  both  must  be  regarded,  from  their  position  and 


Fig.  19.— Sketch  section  of  wall  of  Hackberry  Canyon  at  Hackberry  Spring. 

1.  White  decomposed  rhyolite. 

2.  Pyroxene-andesite. 

3.  Conglomerate  and  soft  sandstone  (Pliocene  ?). 

4.  Thin-bedded,  slaggy  olivine-basalt  (Pleistocene). 

5.  Thin-bedded  slaggy  tordrillite  (siliceous  rhyolite )  (Pleistocene.) 


their  relation  to  the  underlyius 
tocene  (fig.  19). 


rocks  and  to  the  tojiograph}^,  as  Pleis- 


PLEISTOCENE    GRAVELS. 

Through  all  the  rocks  previousl}^  described,  except  part  of  the 
Pleistocene  rhj^olites  and  basalts,  the  drainage  has  cut  a  canyon  in 
places  as  much  as  2,000  feet  deep.  The  detritus  removed  b}^  this 
cutting  has  chiefly  been  carried  down  the  valley  and  out  to  the  Colo- 
rado River,  but  a  certain  portion  still  floors  the  vallej^  bottom. 


SEQUENCE    OF   EVENTS. 

Out  of  the  complicated  conditions  observed  at  so  many  points  in 
the  valley  of  Meadow  Creek,  the  following  rough  sequence  of  events 
may  be  provisionallj^  laid  down : 

1.  Deposition  of  the  Paleozoic  series  of  quartzites  and  limestones. 

2.  Elevation  of  this  series  to  a  land  mass  and  the  erosion  of  the 
rocks  to  produce  a  system  of  mountains  and  valleys.  This  was 
attended  hy  little  or  no  folding. 

3.  Pouring  out  of  great  masses  of  white  biotite-rhyolite  (early 
Tertiary.) 

4.  The  formation  of  a  series  of  water-laid  rhvolitic  sandstones  and 


148  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

tuffs,  interbeclded  Avith  thin  sheets  oL"  rhyolite  and  rhyolite  bveccias. 
This  wliole  series  is  ronglily  estimated  at  4,000  feet  thick  and  at  the 
top  contains  relatively  more  tuffs,  while  at  the  bottom  there  are  rela- 
tively more  lavas.  Several  slight  unconformities  and  manj^  slight 
erosion  gaps  occur  in  the  series. 

5.  Folding  to  a  considerable  degree  of  the  whole  crust. 

6.  Explosive  eruptions  of  pyroxene-andesites  and  latites  of  mod- 
erate extent. 

7.  The  formation  of  a  series  of  water-laid  brown  volcanic  tuffs  or 
sandstones  and  breccias,  with  interbedded  quartz-bearing  volcanics, 
chiefly  dacites  and  reddish  rhyolites.  The  sandstones  were  relatively 
thick  at  the  bottom  of  the  ^series,  the  volcanics  at  the  top.  The  entire 
thickness  of  the  series  is  estimated  at  3,500  feet.  There  are  some 
petty  erosion  intervals. 

8.  General  folding,  comparatively  gentle. 

9.  Deposition  of  at  least  2,000  feet  of  brown  or  red  conglomerates 
and  soft  sandstones,  which  are  accompanied  by  very  few  volcanic 
flows  and  so  are  distinct  from  the  preceding  formations.  They  have 
remained  nearly  horizontal  and  are  probably,  in  large  part  at  least, 
lake  beds.     They  have  been  referred  to  the  Pliocene. 

10.  Drainage  of  the  Pliocene  lake,  erosion  and  slight  local  folding 
in  the  Pleistocene. 

11.  Outpouring  of  thin  sheets  of  rhyolite,  tordrillite,  and  pyroxene- 
olivine-basalt. 

12.  The  formation  of  a  small  amount  of  high  stream  gravels. 

13.  Cutting  down  of  the  canyon  bed  to  its  present  position. 

The  thickness  of  the  basal  rhyolite  is  not  known.  A^ver}^  roughly 
estimated  section  of  the  overlying  formations  is  as  follows: 

Section  in  Meadoio  Valley  Canyon. 

Feet. 

Rhyolite  tiTff  series 4,000 

Andesite : 600 

Red  lava  and  'sandstone .__._. 3, 500 

Pliocene  sandstones  and  conglomerates  ... . . 2, 500 

Total 10,600 

The  succession  of  lavas,  so  far  as  can  be  made  out  in  this  confused 
section,  is  as  follows:  Biotite-rhj^olite,  p^a-oxene-andesite,  biotite- 
hornblende-quartz-latite,  biotite-hornblende-dacite,  quartz-latite  or 
red  rhyolite  and  tordrillite,  pyroxene-olivine-basalt,  glassj^  rhyolite 
or  tordrillite. 

MEADOW  VALLEY  RANGE. 

The  Meadow  Yalloy  Range  lies  oi)posite  the  Mormon  Range,  on  the 
west  side  of  Meadow  Valley.  It  is  comparatively  low  and  irregular. 
At  the  north  end  it  i)asses  into  tlie  Highland  Range  and  at  the  south 


SHL'RR]  MEADOW    VALLEY    RANGE.  149 

into  Las  "S^eg'as  Range,  with  which  it  forms  a  V.     Near  this  point  it 
lioeonies  broader  and  divides  into  several  parallel  petty  ridges. 

SEDIMENTARY   ROCKS. 
The  Meadow  Valley  Range  is  composed  chiefly  of  stratified  rocks. 

CAMBRIAN. 

I'he  mining  camp  of  Delamar  is  situated  on  the  western  slope  of 
the  Meadow  Vallej'  Range.  According  to  Mr.  Emmons^'  the  range 
here  consists  of  limestones  underlain  by  heavy  quartzites,  these  for- 
mations corresponding  to  the  Cambrian  quartzites  and  the  limestones. 
There  is  a  belt  of  shale,  as  at  Pioche.  These  rocks  are  continuous 
northward  into  the  Highland  Range,  but  on  the  east  are  overlain  by 
later  volcanics. 

CARBONIFEROUS. 

Along  the  road  which  crosses  the  range  from  Moapa  toward  Pah- 
ranagat  Valley  an  excellent  section  is  obtained.  Tlie  rocks  are 
Paleozoic  limestones  and  form  two  synclinal  ridges,  with  an  interior 
anticlinal  valley  between.  The  eastern  part  of  the  section  con- 
sists of  rather  thin-bedded  limestone,  full  of  chert  nodules.  These 
apparently  overlie  the  strata  of  the  westernmost  ridge,  which  are 
dark-blue,  semicrystalline  limestones,  also  full  of  chert  nodules,  and 
containing  some  quartz  veins.  This  is  often  fetid,  and  is  more  mass- 
ive and  of  older  appearance  than  the  other  limestones  of  the  section. 

Where  the  road  cuts  through  the  low  eastern  ridge  the  follow- 
ing Upper  Carboniferous  fossils  were  found,  as  determined  by  Dr. 
Girty: 

Fusiilina  cylindrica. 
Archaeocidaris  sp. 
Productus  pratteniamis. 
Prodtictiis  semiretictilatus. 

From  the  apparently  lower  rocks  of  the  western  ridge  the  following 
fossils  were  collected  (also  Upper  Carboniferous): 

Zaphrentis  sp. 
Productus?  sp. 
Spirifer  sp. 
Seminula  sp. 
Macrocheilina?  sp. 

Between  the  western  ridge  and  the  eastern  face  of  the  New  Moun- 
tains to  the  west,  which  are  an  important  branch  of  Las  Vegas  Range, 
a  low  ridge  runs  along  the  middle  of  the  valley,  joining  the  more 
massive  mountains  on  the  south  at  the  angle  of  the  V.     This  ridge 

a  Oral  oommunication. 


150  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

is  composed  of  fetid  tliin-bedded  limestones,  like  those  just  described. 
The  following-  fossils  were  found  by  Dr.  Girty  to  be  Upper  Carbon- 
iferous : 

Fusulina  cylindrica. 
Syringopora  niultattentiata. 
Productus  semireticulatus. 
Productus  prattenianus. 
Pleiirotomaria  sp. 

PLIOCENE. 

The  Pliocene  of  the  southern  portion  of  Meadow  Valley'^  extends 
westward  and  forms  the  flanks  of  the  Meadow  Valley  Range,  abut- 
ting nnconformably  against  the  upturned  Paleozoic  limestones.  The 
rocks  consist  of  horizontal  red  and  white  sandstones  and  occasional 
conglomerates,  varied  a  short  distance  east  of  Moapa  by  a  white  con- 
solidated volcanic  ash.  The  Pliocene  strata  occupy  a  broad  belt 
running  north  and  south.  They  are  locall}^  slightly  folded,  dipping 
as  much  as  10°,  but  in  general  are  horizontal. 

On  the  western  side  of  the  range,  in  the  bay  between  it  and  the 
New  Mountains  and  Las  Vegas  Range,  the  same  Pliocene  sandstones 
occur. 

Some  distance  north  from  Moapa  and  just  northwest  from  Hack- 
berry  Spring,  as  seen  from  Meadow  Valley,  the  Pliocene  deposits 
seem  to  rise  along  the  flanks  of  the  Paleozoic  Range  until  they  occupy 
broad  areas  covering  the  limestones  on  the  summits  of  the  range, 
they  themselves  being  capped  by  volcanics. 

IGNEOUS   ROCKS. 

In  the  northern  half  of  the  range  a  great  part  of  the  rocks  exposed 
at  the  surface  seem  to  be  volcanics,  undoubtedly  belonging  to  the 
Tertiar}^  and  Pleistocene  flows  already  described  in  Meadow  Valley 
Canj^on.  Thej^  probabl}^  are  associated  with  Tertiary  sediments 
derived  from  them,  like  the  beds  in  the  locality  mentioned. 

STRUCTURE. 

The  northern  end  of  the  range  seems  to  be  chiefly  volcanic,  from 
which  the  underlying  Paleozoics  emerge  in  places.  South  of  here 
appear  volcanics  and  associated  Tertiary  sediments,  and  the  main 
ridge  in  the  whole  southern  part  of  the  range  consists  of  folded  Paleo- 
zoic limestones.  The  structure  in  the  Paleozoic  limestones  consists 
of  open  j)arallel  anticlines  and  synclines,  generally  of  no  great  width 
or  depth.  North  of  the  valley  of  the  Mudd}^  the  central  ridge  is  syn- 
clinal, with  an  anticline  closely  adjacent  to  it  on  the  eastern  flanks 
of  the  ridge.     Irregularities  in  the  erosion  sometimes  bring  this  anti- 

aSee  descriptions  of  Meadow  Valley  Canyon,  Mormon  Range,  and  Virgin  Range,  pp.  131, 
136, 143. 


SPCRR.] 


MEADOW  VALLEY  AND  FAHROC  RANGES, 


15X 


eline  to  the  crest  of  the  ridge,  as  shown 
in  a  section  observed  northwest  of  Kane 
Spring.  Just  west  of  Grapevine  Spring, 
however,  the  syncline  forms  the  summit. 

South  of  Mudd}'  Yalle}^  on  the  road 
wliich  runs  westward  from  Moapa,  the 
bioadening  and  dividing  range  shows  two 
principal  synclinal  ridges  with  an  interven- 
ing nonpersistent  anticlinal  valley.  The 
SA'ucline  of  the  westernmost  of  these  ridges 
appears  to  be  continuous  with  the  main  sj^n- 
clinal  ridge  farther  north.  Besides  these 
main  folds  several  petty  ones  were  ob- 
served to  the  east  of  the  easternmost  large 
syncline,  consisting  of  slight  alternating- 
anticlines  and  sj^nclines.  In  the  whole 
section  no  less  than  six  adjacent  open 
folds  were  observed,  the  sjniclines  gener- 
ally forming  ridges,  the  anticlines  depres- 
sions. West  of  the  westernmost  syncline, 
a  low  Carboniferous  ridge  in  the  valley 
has  a  westerly  clip,  and  in  the  depres- 
sion between  it  and  the  synclinal  ridge 
is  an  anticline,  as  is  shown  in  the  moun- 
tains which  terminate  the  depression  be- 
tween the  two  ridges  a  few  miles  farther 
south  (fig.  20). 

PAHROC  RANGE. 

The  Pahroc  is  a  comparatively  short 
range  of  no  great  height,  lying  immedi- 
ately west  of  the  Highland  Range  and 
having  a  due  north-south  trend.  Its  length 
is  not  over  25  miles  and  its  width  not 
more  than  5  or  6  miles.  Only  the  north- 
ern part  of  the  range  was  seen  by  the 
writer,  and  that  from  a  distance  of  several 
miles. 

IGNEOUS   ROCKS. 

Mr.  Gilbert^'  rej)orts  that  the  Pahroc 
Range,  on  the  road  from  Hiko  to  Pioche,  is 
of  lava,  which  extends  a  number  of  miles 
north  and  south. 


Z   I 


't3    3 


lA/icddy  CreeTc 
jMoapa.    '^ 


«  U.  S.  Geog.  Sui-v.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  123. 


152  GEOLOGY    OF    NEVADA   SOUTH    OB^    dOTH    PARALLEL,     [bull.208. 

SEDIMENTAPa"    ROCKS.  I 

As  seen  fi-oin  the  north,  the  northern  end  of  the  range  is  made 
up  of  stratified  roeli;s  of  moderate-l}^  tliick  bedding,  evident!}"  lime- 
stones. These  rocks  extend  for  some  distance  fartlier  south.  Judg- 
ing from  the  rocks  found  just  north  of  liere,  in  the  low  hills  Avhich 
have  been  described  as  forming  the  connection  between  the  Pahroc 
Range  and  the  southern  end  of  the  Egan  Range  a  short  distance 
northwest  of  Pioche,"  the  rocks  of  the  Pahroc  Range  thus  exposed  are 
perhaps,  in  part  at  least,  Devonian.  The  Silurian  may  possibly  be 
represented. 

STRUCTURE. 

The  limestones  which  constitute  the  northern  end  of  the  range  seem, 
when  viewed  from  a  distance,  to  be  bent  into  a  single,  regular,  anti- 
clinal fold,  which  strikes  parallel  to  the  north-south  trend  of  the  range. 
The  summit  of  the  range  appears  to  com^jrise  the  axis  of  the  fold,  and 
from  this  the  rocks  dip  on  l)oth  sides  at  a  gentle  angle,  averaging 
about  15°. 

HIKO  RANGE. 

The  Hiko  Range  lies  next  southwest  of  the  Pahroc  Range,  with 
which  it  is  joined  at  several  points  by  low  connecting  hills.  It  has  a 
north-south  extent  of  about  30  miles,  and,  like  the  Pahroc  Range,  its 
general  trend  hardly  diverges  from  a  due  north-south  line.  On  the 
west  the  Hiko  Range  is  connected  by  a  series  of  hills  with  the  Pahran- 
agat  Range,  and  this  series  of  hills  continued  farther  Avest  connects 
these  ranges  Avith  the  Timpahute  Range  and  the  Worthington  Moun- 
tains.    Like  the  Pahroc  Range,  .the  Hiko  Range  is  comparatively^  Ioaa'. 

SEDIMENTARY    ROCKS. 

Most  of  the  Hiko  Range  is  composed  of  limestone  of  Silurian  and 
DcA'onian  ages.  Mr.  Gilbert*  first  described  Silurian  fossils  from 
Fossil  Butte,  just  Avest  of  the  main  range.  Subsequentlj^  Mr.  Wal- 
cott  ^  made  an  investigation  of  the  paleontology  here,  and  described 
many  species  of  fossils.  According  to  Mr.  Walcott  there  is  exposed 
in  Fossil  Butte  the  Pogonip  limestone  of  the  Eureka  series,  overlain 
by  the  Eureka  quartzite.  Near  Hiko  he  found  shaly  limestone,  OA^er- 
lain  by  arenaceous  limestone  carrying  a  DcA^onian  fauna. 

IGNEOUS   ROCKS. 

Accoi'ding  to  Mr.  Gilbert,'^  there  are  a  fcAV  small  bodies  of  laA^a  in 
the  range. 


a  See  description  of  Egan  Range,  p.  49. 

&U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  A^ol.  Ill,  p.  181. 

o  Mon.  U.  S.  Geol.  Survey  Vol.  XX,  p.  195. 

d  Op.  cit.,  p.  123. 


SPUKR]  HIKO    AND   PAHRANAGAT    RANGES,  153 

STRUCTURE. 

Mr.  Gilbert «  found  in  the  Hiko  Range  north  of  Fossil  Butte  a 
westerly  clip,  but  south  of  this  point  an  easteii}^  dip.  There  has 
been  no  folding,  and  therefore*  there  is  a  scissors  fault'''  transverse 
to  the  range  at  about  this  point.  This  same  peculiar  structural 
feature,  according  to  Mr.  Gilbert,  is  characteristic  of  all  the  ridges 
west  of  here  as  far  as  the  Tinipahute  Range. 

PAHRANAGAT    RANGE. 

The  Pahranagat  Range  lies  next  southwest  of  the  Hiko  Range, 
with  which  it  is  connected  at  its  northern  end  by  Fossil  Butte.  From 
here  it  extends  southward  in  a  general  south-southeasterly  direction 
for  about  40  miles,  where  it  is  separated  from  the  Arrow  Canj^on 
Mountains  by  a  comparatively  short  transverse  stretch  of  desert 
valley.  The  highest  mountain  in  the  range  is  Quartz  Peak,  at  its 
northern  end. 

SEDIMENTARY   ROCKS. 

Mr.  Gilbert^  found  Silurian  fossils  in  the  northern  end  of  the 
range.  Mr.  Walcot t '^' found  on  the  eastern  side  of  the  Pahranagat 
Range  limestones  which  he  regarded  as  possibly  belonging  to  the 
Lone  Mountain  series  of  the  Silurian.  In  Quartz  Peak,  just  west  of 
here,  he  found  a  fine  exposure  of  Silurian  strata  comprising  the  fol- 
lowing divisions: 

Section  at  Quartz  Peak. 

Feet. 

Lone  Mountain  Niagara 535 

Lone  Mountain  Trenton 515 

Eureka 400 

Pogonip . 750 

Total '. 2, 200 

South  of  Quartz  Peak  he  found  a  great  thickness  of  limestone, 
nearl}^  8,000  feet  in  all,  broken  onlj'^  by  thin  beds  of  yellow  sandstone, 
the  heaviest  not  over  100  feet  in  thickness.  In  this  g'reat  thickness 
of  limestone  he  found  no  lithologic  variation  sufficient  to  base 
divisions  upon.  From  the  fossils  contained  he  found  that  the  lime- 
stone ranged  from  Carboniferou-^  through  the  Devonian  into  the 
Silurian.      It  was  impossible    to    draw    any    line   of    demarcation 

«  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill, p.  39. 

bThe  writer  has  employed  this  term  thinking  that  it  was  already  in  use.  Mr.  Gilbert,  how- 
ever, who  has  examined  the  manuscript,  believes  that  the  term  is  original  here,  and  it  is  there- 
fore defined  as  a  fault  whose  movement  is  like  that  of  a  pair  of  scissors  when  opened,  there  being 
on  the  fault  plane  an  axis  where  the  differential  movement  is  nothing,  while  on  one  side  of  this 
axis  the  movement  is  the  reverse  of  what  it  is  on  the  other.  Therefore  the  rocks  on  the  two 
sides  of  the  fault  plane  will  acquire  tilts  in  opposite  directions. 

<-Op.cit.,pp.l68,181. 

dMon.  U.  S.Geol.  Survey  Vol.  XX, p.  196. 


154  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

between  the  Silurian  and  Devonian,  but  dividing  the  rocks  as  well  as 
might  be  the  following  thicknesses  were  fonnd: 

Feet. 

Carboniferous  _ . 2, 160 

Devonian * ._  _ .  5, 400 

Silurian  _._. 1,000 

IGNEOUS  ROCKS. 

Mr.  Walcott  noted  occasional  outbursts  of  acidic  lavas  in  the  Pah- 
ranagat  Range,  and  Mr.  Gilbert  describes  two  large  eruptions  of 
rhyolite,  one  at  the  north  end  of  the  range  and  the  other  at  Logan 
Pass  at  a  cross  fault. 

STRUCTURE. 

According  to  Mr.  Gilbert  the  cross  fault  above-mentioned  is  a  scis- 
scors'*  fault,  having  such  differential  movement  that  all  the  strata  to 
the  north  acquired  a  westerly  dip,  while  those  to  tlie  south  are  tilted 
toward  the  east.  That  portion  of  the  range  which  lies  north  of  the 
cross  fault  is  divided  into  separate  north-south  ridges  by  north-south 
faults  whose  downthrow  has  been  uniformly  to  the  east.  South  of 
the  pass  the  strata  have  a  single,  monoclinal,  easterly  dip. 

ARROW  CANYON   RANGE. 

The  Arrow  Canyon  Range  has  not  been  visited  and  was  onlj^  seen 
from  some  little  distance.  It  is  a  continuation  northward  of  that 
branch  of  Las  Vegas  Range  which  has  been  called  the  New  Mountains. 
It  has  a  general  northwesterly  trend,  j)arallel  with  the  main  west  arm 
of  Las  Vegas  Range,  and  has  a  length  of  more  than  20  miles.  On 
the  north  it  is  separated  from  the  Pahranagat  Range  by  a  nari-ow, 
transverse  valley. 

As  seen  from  several  points,  the  Arrow  Canyon  Mountains  are  made 
up  of  stratified  rocks,  well  banded,  but  eroded  so  as  to  form  massive 
cliffs.  This  is  the  apijearance  offered  by  the  heavy  Carboniferous 
limestone  of  this  region,  as  shown  just  south  of  here  in  the  New 
Mountains.  It  is  possible,  therefore,  that  the  bulk  of  the  range  is 
Carboniferous.  To  the  north  also,  in  the  Pahranagat  Range,  Carbon- 
iferous rocks  are  present  in  considerable  quantity. 

The  strike  of  the  strata  is  parallel  with  the  trend  of  the  range. 
Along  nearly  the  whole  of  its  western  side  the  rocks  are  seen  to  dip 
into  the  range  eastward  at  angles  of  from  15°  to  20°.  Farther  north 
an  area  of  apparently  horizontal  strata  can  be  distinguished;  so  that 
the  general  structure  of  the  range  maj'^  be  synclinal,  corresponding 
to  that  of  the  New  Mountains  to  the  south,  or  it  may  be  a  general 
monocline  dippiug  eastwardly,  like  the  Pahranagat  Range. 

a  See  p.  153  for  definition. 


SPURR]  AKKOW    CANYON    AND    LAS    VEGAS    RANGES.  155 

LAS  VEGAS  RANGE. 

Las  Vegas  Range  forms  an  irregular  group  in  the  central  portion 
of  southern  Nevada,  lying  just  east  of  another  irregular  group,  the 
Spring  Mountain  Range.  Las  Vegas  Range  has  hardly  any  defijiite 
form,  but  a  prolongation  on  the  northwest  gives  it  rather  the 
aspect  of  having  a  northwesterly  trend.  This  pixjlongation  forms  one 
arm  of  a  rough  V,  of  which  the  southern  portion  of  the  Meadow 
Valle}'  Range  forms  the  other,  the  two  uniting  in  a  rugged  cluster 
of  mountains  in  the  neighborhood  of  Gass  Peak.  Bisecting  the 
angle  of  the  V  is  a  high,  rocky  ridge,  which  was  not  delineated  on  the 
Wheeler  survey  maps,  and  which  the  writer  will  call,  for  the  purpose 
of  description,  the  New  Mountains. 

It  is  peculiar  that  so  prominent  a  ridge  should  have  escaped  map- 
ping, for  it  comprises  some  of  the  highest  mountains  in  the  southern 
part  of  the  State.  On  the  eastern  face  of  the  New  Mountains  is  a 
sharp  scarp  of  about  4,000  feet,  rising  from  the  foothills.  This  scarp 
is  often  perpendicular  for  great  heights,  and  is  apparently  inacces- 
sible. The  rocks  are  composed  of  massive  limestone,  beautifully 
banded.  To  the  north  the  New  Mountains  become  lower  and  are 
separated  from  the  Arrow  Canj^on  Mountains,  which  are  reallj^  a 
portion  of  the  same  general  range,  by  a  transverse  valley. 

The  south-^iBst  face  of  Las  Vegas  Range,  facing  Las  Vegas  Vallej^ 
also  possesses  a  steep  slope,  reaching  45°  at  some  points. 

No  igneous  rock  whatever  was  found  in  Las  Vegas  Range. 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

From  a  point  about  6  or  7  miles  north  of  Mormon  Wells,  which  is  on 
the  wagon  trail  crossing  the  southern  portion  of  the  range  in  a  north- 
easterljT^  direction,  southward  probably  to  the  end  of  the  range,  the 
rocks  consist  chiefly  of  bristly  weathering  siliceous,  crystalline,  cherty 
limestone,  often  having  a  peculiar  mottled  structure,  which  is  proba- 
bly due  to  the  rock  having  been  originally  made  up  of  coral,  now 
recrj'stallized  and  unidentifiable.  This  rock  is  lithologically  identical 
with  Cambrian  limestones  in  the  Highland  Range  west  of  Pioche. 

On  the  divide  south  of  Mormon  Wells  there  are  found  thin,  brown 
and  red,  sandy,  and  limj^  slates,  changing  to  thin-bedded  limestones. 
These  contain  fossil  remains,  which  are  determined  by  Mr.  Walcott 
as  belonging  above  the  OleneUus  zone  and  probably  to  the  Middle 
Cambrian.  Fragments  of  white  quartzite  were  found  in  the  drift  here, 
which  also  suggest  the  existence  of  Lower  Cambrian  quarzites  in  the 
mountains. 

The  same  ancient-appearing  limestones  are  continuously  exposed 
along  the  road  above  mentioned,  southwest  nearly  to  Las  Vegas  Val- 
ley.    At  this  point  they  give  way  to  the  underlying  Silurian. 


156  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

Mr.  R.  B.  Rowe  noted  that  the  first  ridge  west  of  Sheep  or  Gass 
Mountain  (which  ridge  is  here  considered  the  northernmost  part  of 
Las  Vegas  Range)  consists  of  beds  of  dark-blue  and  gv&y  lime- 
stone, with  white  and  reddish  sandstone.  Fossils  collected  in  this 
locality  were  found  b}'  Dr.  Girtj^  to  be  chiefly  Devonian,  but  to  con- 
tain one  Cambrian  specimen.  Therefore,  probably  both  the  Cambrian 
and  the  Devonian  are  here  represented. 

SILURIAN. 

In  the  vallej^  just  northeast  of  Gass  Peak,  at  the  locality  above 
mentioned,  occur  cherty,  blue-graj^  and  siliceous,  sometimes  green 
and  shaly,  limestones  similar  to  those  of  the  Cambrian.  The  few,^ 
fossils  obtained  from  these  rocks  are  regarded  by  Mr.  Walcott  as  rep- 
resenting H  horizon  about  the  base  of  the  Pogonip  (Ordovician).  Mr. 
Walcott  determined  Ortliis  perveta  (?)  and  the  tail  of  a  trilobite 
belonging  to  the  genus  Batliyurus. 

From  this  point  to  the  northwestern  end  of  the  range  the  rocks  ■ 
appear  to  be  all  limestones,  of  the  same  ancient  character  as  tlioise 
already  described,  as  specimcKS  obtained  here  and  there  show.  Ai 
similar  limestone  extends  still  farther  northwest  into  the  southern 
end  of  the  Desert  Range,  and  was  followed  continually  along  Las  Vegas- 
Valley  to  Indian  Spring  in  the  Spring  Mountain  Range.  At  Indian 
Spring  iDrdovician  fossils  were  found. 

About  0  miles  northeast  of  Corn  Creek,  near  the  mouth  of  the  first 
important  canyon,  Mr.  R.  B.  Rowe  found  about  200  feet  of  dark 
blue  limestone,  containing  immense  numbers  of  gasteropods  of  enor- 
mous size,  together  with  a  few  corals.  The  fossils  collected  hy  Mr. 
Rowe  were  determined  bj'  Dr.  Girty  as  Ordovician. 

DEVONIAN. 

The  existence  of  Devonian  limestones  in  the  ridge  west  of  Sheep  or 
Gass  Mountain,  at  the  north  end  of  the  range,  has  already  beeni 
mentioned. 

CARBONIFEROUS. 

The  Cambrian  rocks  in  the  neighborhood  of  Mormon  Wells  are 
apparently  separated  by  a  heavy  east- west  fault  from  the  unmetamor- 
phosed  massive  blue  limestones  which  make  up  the  greater  portion  of 
the  New  Mountain  ridge  and  the  auxiliary  ridges  to  the  east.  In  one 
of  these  auxiliary  ridges  a  collection  of  fossils  was  obtained,  which 
were  found  by  Dr.  Girty  to  be  Upper  Carboniferous.  No  north-south 
faults  were  determined,  and  the  gentle  folding,  resulting  in  slight, 
alternating  synclines  and  anticlines,  suggests  that  rocks  of  the  same 
horizon  make  uji  the  New  Mountains  to  the  west. 

According  to  the  notes  of  Mr.  R.  B.  Rowe,  the  mountains  east  of 
Las  Vegas  contain  the  Lower  Carboniferous,  the  Carboniferous  red 


puRR.l  LAS    VEGAS    KAISTGE.  157 

3eds,  and  the  Upper  Carboniferous  limestone,  so  far  as  can  be  seen 
Tom  Las  Vegas  ranch. 

From  Sheep  or  Gass  Mountain,  in  Las  Vegas  Range,  specimens  of 
(xoniatites  were  brouglit  and  given  to  Mr.  Rowe.  The  fossils  seem  to 
3ome  from  a  soft  shale.'* 

About  2  miles  west  of  Sheep  or  Gass  Mountain,  in  a  spur  of  that 
*ange,  about  5  or  G  miles  north  of  the  road  leading  from  Corn  Creek 
j:o  Indian  Creek,  fossils  were  collected  which  were  determined  by  Dr. 

irty  as  Upper  Carboniferous  or  Pennsylvanian,  and  in  the  same 
General  region  other  fossils  were  collected  which  were  determined. by 
Dr.  Girt}'  as  Lower  Carboniferous  or  Mississippian.  The  ridge  con- 
"lists  mainly  of  low  hills,  wliich  are  cut  extensively  by  canyons. 

Terfianj. — -Mr.  R.  B.  Rowe's  notes  on  the  Tertiary  areas  follow. 
lAt  Las  Vegas  and  in  the  immediate  vicinity  there  are  white  beds  of 
probabl}"  volcanic  ash.  From  the  vallej^  some  distance  west  of  Las 
V^egas  mastodon  teeth  were  collected.  About  midwa}^  between  Corn 
Creek  and  Tule  Springs  some  mastodon  teeth  and  bones  have  been 
found.     They  were  situated  in  a  clay  bank  some  10  or  15  feet  high. 

East  of  the  range,  at  the  summit  of  the  pa^ss  between  Las  Vegas 
Valley  and  Muddj^  Creek,  about  12  miles  east  of  Las  Vegas,  are 
fed  and  yellow  Tertiary  beds  which  dip  toward  the  Colorado  River  at 
an  angle  ranging  from  4°  to  5°.* 

The  valley  between  Las  Vegas,  Tule  Springs,  and  Corn  Creek  seems 
to  be  filled  with  lake  deposits.  About  Tule  Springs,  and  from  there 
up  the  valley,  are  probably  the  remnants  of  an  old,  dry  lake  bed  or 
playa.  The  deposits  do  not  have  the  appearance  of  the  Tertiary  lake 
deposits,  but  resemble  exactly  the  clay  deposits  in  the  present  dry 
lakes.  Underlying  these  is  a  gravel  or  talus  deposit.  The  eroded 
drv  lake  beds  extend  froni  Corn  Creek  to  Indian  Creek. 

PLEISTOCENE. 

In  Las  Vegas  Vallej^  the  Tertiary  deposits  so  abundantly  exposed 
in  the  region  of  Meadow  Valley  are  hidden  beneath  Pleistocene 
accumulations.  This  valley  is  of  the  usual  type  of  the  desert  valleys 
of  Nevada,  with  gulch  dumps  fringing  the  mountains,  and  in  the 
center  a  nearly  level  area  of  hard  mud  flats,  or  a  playa.  There  has 
been  no  dissection  of  these  deposits  to  reveal  what  lies  beneath. 

STRUCTURE. 

The  general  folding  in  Las  Vegas  and  New  mountains  has  apparently 
resulted  in  a  rough,  shallow,  disturbed  northeast-southwest  striking 
syncline.    The  nearly  horizontal  area  in  the  central  portion  of  the  range 

« These  maybe  the  same  as  some  specimens  of  Goniatiies  rec3ived  by  Dr.  Girty  from.  Mr. 
Rowe's  collection  after  the  death  of  Mr.  Rowe.  They  were  considered  by  Dr.  Girty  as  Lower  (?) 
Carboniferous. 

''These  are  the  same  as  described  by  the  writer  under  the  head  of    'Meadow  Valley  Range." 


158  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

belongs  in  the  trough  of  thes^^ncline,  while  at  the  northwestern  end  the 
dip  of  the  northwest  limb  of  the  fold  becomes  30°  or  45°  southeasterly, 
or  even  more.  The  sjaicliue  is  succeeded  by  a  much  sharper  anti- 
cline along  the  narrow  valle}^  separating  the  Desert  and  Las  Vegas 
ranges.  In  the  broad  central  portion  of  the  syncline  there  has  been 
irregular  minor  folding,  chiefly  along  east-west  lines,  the  dips  gener- 
ally being  under  15°.  At  the  southern  end  of  the  range  the  general 
strike  appears  to  become  east  and  west,  and  the  dip  about  20°  north. 

The  main  fold  of  Las  Vegas  Range,  being  at  right  angles  to  the 
general  trend  of  the  mountains,  runs  across  Las  Vegas  Valley  and  is 
probably  to  be  found  in  the  Spring  Mountain  Range  on  the  other  side, 
where,  indeed,  it  Avas  thought  to  have  been  identified  by  the  writer. 
Similarly,  the  various  ijarallel  ridges  of  limestone  which  run  trans- 
verse to  the  general  trend  of  the  range  are  broken  by  the  valley  and 
find  their  continuation  in  the  Spring  Mountain  Range  opposite.  Las 
Vegas  Valley,  therefore,  differs  from  the  most  ordinary  type  in  the 
Great  Basin  in  that  it  is  transverse  to  the  general  strike  of  the  rocks. 

In  the  region  north  of  Mormon  Wells  there  is  a  marked  change 
from  massive,  unaltered,  blue  limestones,  probably  belonging  to  the 
Carboniferous,  to  altered,  ancient-appearing,  crystalline  limestones, 
associated  with  shales  can-ying  Cambrian  fossils.  The  areas  occupied 
by  these  different  rocks  may  be  easily  sketched,  since  the  erosion  of 
each  has  resulted  in  peculiar  forms.  The  Cambrian  rocks  have 
rounded  topography,  without  scarps  or  evident  structure,  and  weather 
brown,  while  to  the  north  the  blue-gray  Carboniferous  rocks  have 
sharp  scarped  outlines  with  perfectly  visible  stratification.  Inasmuch 
as  the  strike  of  the  folds  is  here  north  and  south,  which  carries  the 
Carboniferous  limestone  directly  into  the  Cambrian,  there  must  be  a 
fault  between  tlie  two  horizons,  and  this  fault  must  have,  as  sketclied, 
a  direction  somewhat  north  of  west.  The  vertical  disj)lacement  of  the 
fault  maj^  be  several  thousand  feet  and  has  resulted  in  a  downthrow 
to  the  north.  There  is  no  distinct  brealv  in  the  topography  along  the 
fault  line. 

The  bold  east  face  of  the  New  Mountains  suggests  a  more  recent 
heavy  fault,  to  whose  displacement  the  scarp  maj^  perhaps  be  directly 
due. 

The  following  notes  on  the  structure  were  made  by  Mr.  R.  B.  Rowe: 

A  sketch  of  the  mountains  of  Las  Vegas  Range  east  of  Las  Vegas 
shows  a  constant  dip  of  about  40°  to  the  east.  A  hypothetical  fault 
is  also  shown,  which  has  the  effect  of  bringing  up  the  lower  strata  on 
the  east  side. 

In  ear  Corn  Creek  the  rocks  strike  east  and  west  and  dip  uniformly 
30  °  to  the  north. 

As  has  been  noted,  there  is  a^jparently  a  series  of  old,  dry  lake 
deposits  in  Las  Vegas  Valley,  which  are  now  being  cut  into  by 
the  arroyos.  These,  taken  together  witli  the  fact  that  the  surface 
rises  about  400  to  600  feet  between  Tule  Sjarings  and  Com  Creek 


SPURR.]  TIMPAHUTE    RANGE.  159 

and  that  the  same  beds  rise  still  higher  bej^on«l  Corn  Creek,  indicate  a 
comparatively  recent  elevation  of  the  upper  end  of  Las  Vegas  Valley. 
On  the  east  side  of  Las  Vegas  Range,  the  fact  that  the  Tertiary 
beds  dip  slightly  toward  the  Colorado  at  an  angle  of  4°  or  5°  suggests 
that  the  Las  Vegas  Range  has  been  slightly  raised  since  the  general 
elevation  of  the  region. 

TIMPAHUTE  RANGE. 

The  following  summary  of  the  Timpahute  Range  is  taken  from 
Mr.  Gilbert's  description." 

The  Timpahute  Range  lies  next  west  from  the  Pahranagat  Range 
and  immediately  south  of  the  Worthington  Mountains.  Its  general 
trend  is  a  little  east  of  north  and  its  length  about  30  miles.  The 
highest  portion  is  Timpahute  Peak,  near  the  southern  end. 

SEDIMENTARY    ROCKS. 

At  the  south  end  of  the  range  Mr.  Gilbert  *  measured  a  thickness 
of  2,325  feet  of  strata  showing  the  following  section: 

Section  at  south  end  of  Timpahute  Range. 

Feet. 

1.  Heavy-bedded  gray  limestone,  light  and  dark 400 

2.  Yellow  argillaceoiis  shale: 

a.  Yellow  shale,  350  feet .._ -. 

b.  Yellow  sandstone,  75  feet | 

c.  Yellow  and  green  shale,  with  fillets  of ,  fossiliferons  limestone  | 

(Conoconjphe) ,  500  feet J 

3.  Piarple,  ripple-marked,  vitreoiTS  sandstone,  with  bands  of  siliceous  shale.  1, 000 

Total -.  2,325 

The  fossils  found  in  the  shales  above  the  basal  quartzite  fix  the 
formation  as  Cambrian,  and  the  basal  quartzite  is  the  same  as  the 
basal  quartzite  of  the  Highland  Range  Cambrian  section  and  also 
the  Prospect  Mountain  quartzite  at  Eureka." 

The  northern  portion  of  the  range  does  not  appear  to  have  been 
described.  Both  to  the  east  and  to  the  west  of  it,  in  the  Worthing- 
ton Mountains  and  in  the  Pahranagat  Range,  are  Silurian  rocks,  in 
part  Lower  Silurian.  It  is  probable,  therefore,  that  this  north  end  of 
the  Timpahute  Range  is  in  part  Silurian  and  in  part  also  Cambrian. 

IGNI]OUS   ROCKS. 

According  to  Mr.  Gilbert,'^  Timpahute  Peak  is  the  center  of  a 
massive  eruj)tion  of  rhyolite,  which  connects  with  a  similar  eruption 
northeast  of  here  in  the  Pahranagat  Range  by  a  line  of  volcanic 
hills  which  runs  across  the  intervening  valley. 

aJJ.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  III. 
6Ibid.,  p.  169. 

cTbid.,  p.  181;  C.  D.  Walcott,  Bull.  U.  S.  Geol.  Survey  No.  30,  p.  30,  Bull.  81,  p.  156:  Arnold  Hague, 
Men.  U.  S.  Geol.  Survey  Vol.  XX,  pp.  45, 189. 
''Op.  cit.,  p  123. 


925 


160  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PAEALLEL.     [bull.208. 

STRUCTURE. 

The  volcanic  outburst  at  Tiinpaliute  Peak,  according  to  Mr.  Gil- 
bert/' is  on  the  line  of  a  scissors  fault,  whicli  has  so  displaced  the 
strata  that  to  the  north  of  this  fault  they  dip  uniformly  west  while  to 
the  south  thej^  dip  nniformly  east.  This  fault  is  on  the  same  line  as 
a  similar  fault  northeast  of  here  in  the  Pahranagat  Range,  and 
another  still  farther  northeast  in  the  Hiko  Range,  and  in  each  of 
these  ranges  the  peculiar  tilting  of  the  strata  above  noted  is  found. 
In  the  Timpahute  Range  the  sedimentary  rocks  south  of  the  line  of 
faulting  are  separated  by  north-south  vertical  faults  which  have  a 
uniform  downthrow  to  the  west.  Mr.  Gilbert  gives  a  section  of  the 
range  showing  this  structure. 

ORE    DEPOSITS. 

In  the  Cambrian  shales  at  the  southern  end  of  the  range,  according 
to  Mr.  Gilbert,^  are  metalliferous  veins. 

DESERT  RANGE. 

The  Desert  Range  is  somewhat  irregular  and  of  moderate  height. 
It  is  divided  into  two  branches  by  an  interior  valley  which  reaches 
northward  from  the  north  end  of  the  Spring  Mountain  Range.  At 
its  north  end  the  Desert  Range  passes  into  the  valley  which  sepa- 
rates the  Timj)ahute  from  the  Pahranagat  Range. 

SEDIMENTARY    ROCKS. 

The  south  end  of  the  Desert  Range  was  visited  by  the  writer.  It 
consists  of  altered,  crystalline,  light-gray  limestone,  brown  weathei-- 
ing,  often  full  of  rounded,  detrital  quartz  grains.  There  are  also 
beds  of  black,  dense  limestone.  Similar  limestone  contains  Ordovi- 
cian  (Pogonip)  fossils  in  the  western  part  of  Las  Vegas  Range.  This 
limestone  series  can  be  distinguished  extending  northward  fully  half- 
way to  the  end  of  the  range,  at  least  20  miles.  It  is  possible  that  it 
may  contain  some  of  the  Cambrian  limestones  which  are  hardly 
separable  lithologically  from  the  overlying  Silurian. 

Mr.  F.  B.  Weeks''  followed  along  the  west  side  of  the  range  and 
crossed  the  north  end,  at  Mud  Spring,  in  1900.  He  found  the  bulk 
of  the  range  to  consist  of  stratified  rocks,  which  he  was  inclined  to 
consider  as  Silurian  and  Devonian,  while  on  the  north  end  these 
strata  are  replaced  by  volcanic  rocks. 

The  following  notes  were  made  b}^  Mr.  R.  B.  RoAve:'^ 

SILURIAN. 

About  8  or  9  miles  northeast  of  Indian  Creek,  in  the  first  range  on 
the  west  side  of  the  dry  lake  which  lies  east  of  Indian  Creek,  and  about 


«U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp. ! 

Mbid.,p.  181. 

c  Personal  communication  to  the  writer. 

f' Taken  from  his  notebooks  after  his  death  by  the  writer. 


spiTRR.]  DESEET    AND    REVEILLE    RANGES.  161 

•4  miles  north  of  the  road  from  Indian  Creek  to  Corn  Creek,  tlie  section 
consists  chiefly  of  dark-bine  limestone,  with  light-bine  arenaceons 
limestones  and  shaly  limestones  with  chert  layers.  There  are  also  a 
few  layers  of  white  sandstone,  resembling-  qnartzite.  Fossils  collected 
were  regarded  by  Mr.  RoAve  as  Ordovician,  and  his  impression  was 
corroborated  by  Dr.  Girty's  examination. 

The  rocks  4  miles  east  of  Indian  Creek  are  light-gray,  arenaceons, 
and  dark-bine  limestones,  with  laj^ers  of  chert  and  white  sandstone, 
which  is  nearly  a  qnartzite,  as  it  is  farther  east.  These  rocks  were 
regarded  b}'^  Mr.  Rowe  as  probably  Lower  Silnrian. 

DEVONIAN. 

Abont  o  miles  northeast  of  Indian  Creek,  in  low  hills  sonth  of  the 
road  leading  to  the  lower  end  of  Pahranagat  Valle}^  and  north  of  the 
road  to  Corn  Creek,  fossils  were  found  in  loose  blocks  of  dark-blue 
limestone.  These  were  regarded  by  Mr.  Rowe  as  Middle  Devonian, 
and  were  determined  by  Dr.  Girty  as  probably  Lower  Devonian. 

STRUCTURE. 

At  its  southern  end  the  range  is  separated  on  the  southwest  from 
Las  Vegas  Range  by  a  narrow  anticlinal  valley,  the  rocks  of  the  Desert 
Range  dipping  northwest  on  the  northwest  limb  of  the  fold.  The 
general  strike  here  is  northeast,  and  a  series  of  parallel  ridges  has 
been  eroded  parallel  to  the  strike.  The  dip  continues  in  the  same 
direction  as  far  as  the  interior  valley  dividing  the  two  chief  branches, 
but  becomes  flatter,  and  the  strike  swings  around  more  toward  the 
north.  On  the  western  branch  of  the  range,  as  seen  from  the  south, 
the  rocks  are  j)artly  horizontal  and  partly  strike  a  little  east  of  north 
and  dip  uniformly  west  at  angles  not  exceeding  15°. 

The  valley  lying  between  the  ridge  lying  west  of  Sheep  Mountain 
and  the  range  next  west,  or  between  Las  Vegas  Range  and  the  Desert 
Range,  was  regarded  by  Mr.  Rowe  as  anticlinal  in  structure."  The 
mountains  on  the  two  sides  dip  in  opposite  directions.  On  the  west- 
ern side  Ordovician  fossils  were  found ;  on  the  eastern  side  Carbonif- 
erous and  Cambrian.  There  are  probably  large  and  numerous  faults 
concealed  by  the  talus.  There  is  a  great  deal  of  plainly  observable 
faulting  at  right  angles  to  the  strike.  These  faults  are  generally  not 
large,  but  are  abundant.* 

REVEILLE  RANGE. 

The  Reveille  Range  is  separated  on  the  north  from  the  Pancake 
Range  by  a  narrow  transverse  gap  at  Twin  Sijrings.  It  extends 
southeastward  from  here  a  distance  of  about  60  miles,  running 
obliquely  across  to  the  Timpahute  Range. 


"This  is  the  same  anticlinal  valley  that  was  previously  observed  by  the  writer  (see  above) 
(J.E.&.). 
bThis  whole  paragraph  is  from  Mr.  Rowe's  notes. 

Bulk  208—03 11 


162 


GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 


TOPOGRAPHY. 

The  range  is  somewhat  irregular  in  its  course  and  extent,  which 
arises  from  its  being  made  up  largely  of  volcanic  outbursts.  This 
also  accounts  for  the  prevalent  tj^pe  of  topography,  which  is  similar 
to  that  of  the  Pancake  Range  to  the  north,  showing  low  peaks  and 
broad,  gently  sloping  mesas,  which  are  sharply  cut  into  by  the  valleys 
eroded  since  the  period  of  lava  effusion.  At  one  or  two  points,  how- 
ever, such  as  that  near  the  old  mining  camp  of  Reveille,  xjatches  of 
older  Paleozoic  strata,  and  of  older  volcanics  than  those  which  form 
tlie  mesa-like  forms,  emerging  from  the  younger  lavas,  offer  a  series- 
of  sharp,  irregular  peaks  and  better  developed  valleys. 


SEDIMENTARY    ROCKS. 

According  to  Mr.  Gilbert,"  the  Paleozoic  strata  which  form  the  core 
of  the  Reveille  Range  are  exposed  at  but  two  points,  one  at  Reveille 
and  the  other  60  miles  farther  south.  In  both  these  cases  the  rocks 
dip  to  the  west,  the  dip  being  steeper  at  the  more  southern  exposure. 
At  Reveille  the  strata  are  of  limestone  and  quartzite. 


Fig.  31.— Generalized  sketch  cross  section  of  Reveille  Range  near  Reveille. 

1.  Paleozoic  (Cambrian)  quartzite  (la)  and  limestone  (lb).       4.  Rhyolite  sandstone. 

2.  Rhyolite.  5.  Olivine-basalt. 

3.  Porphyry  dikes.  .  6.  Valley  wash  (Pleistocene). 

The  more  northerly  locality  was  Adsited  by  the  writer,  and  so  far  as 
a  hasty  examination  could  determine,  the  lowest  formation  seems  to 
be  a  hard  white  quartzite,  surmounted  by  a  dark-blue  massive  lime- 
stone, much  altered  and  cariying  only  indeterminable  fossils.  As 
seen  from  Reveille,  the  mountain  to  the  east  seems  to  have  at  its  base 
about  1,500  feet  of  quartzite,  capped  by  2,000  feet  of  limestone.  The 
strike  is  north  and  south,  the  dip  W.  15°  or  20°.  If  the  section  is 
actually  as  supijosed,  the  rocks  can  hardly  be  other  than  the  Cam- 
brian quartzite  and  limestone  of  the  Eureka  section.^ 

The  strata  are  traversed  by  many  i^orphjay  dikes,  probabl}^  con- 
nected with  the  rhyolitic  outbursts.  The  rhyolite  wraps  around  these 
limestone  mountains  in  such  a  way  as  to  show  that  they  were  already 
sharp  peaks  previous  to  the  pouring  out  of  the  lava  (fig.  21). 

nU.  S.  Geog.  Surv.  W.  One  hundredth  Mer.,  Vol.  Ill,  p.  37. 

6  Ibid.,  p.  1V9,  Mr.  Gilbert  cites  Prof.  J.  J.  Stevenson  as  having  recognized  Carboniferous  rocks 
at  Reveille.  In  view,  however,  of  the  confusion  of  Carboniferoiis  and  older  rocks  at  this  period 
(several  other  Cambrian  areas  having  been  referred  to  the  Carboniferous)  and  in  view  of  the 
fact  that  the  lithology  of  the  region  is  that  typical  of  the  Cambrian  here,  but  probably  not 
chai'floteristic  of  the  Carboniferous,  the  writer  has  decided  to  retain  in  the  mapping  the  Cambrian 
color. 


SPURR.]  EEVEILLE    AND    BELTED    RANGES.  163 

TERTIARY. 

In  the  transverse  cut  across  the  northern  end  of  the  mountain  range 
at  Twin  Springs  the  section  consists  of  volcanic  rocks  and  water-laid 
tuffs  and  gravels  derived  from  them.  At  the  base  of  the  section  is 
altered  biotite-rhyolite,  and  above  comes  about  (300  feet  of  white 
rhyolitic  sandstone.  This  is  (japped  by  100  feet  of  rhyolitic  tuffs  and 
gravels,  surmounted  by  about  100  feet  of  angite-olivine-basalt. 

IGNEOUS   ROCKS. 

As  already  stated,  most  of  the  range  is  made  up  of  igneous  rocks. 
Those  Avliich  outcrop  most  upon  the  surface  appear  to  belong  to  the 
later,  more  basic  lavas,  of  which  the  augite-olivine-basalt  at  Twin 
Springs  is  a  member.  This  same  basalt  is  found  on  the  east  of  the 
higher  mountains  between  Twin  Sjirings  and  Reveille.  Beneath  this 
basic  lava,  however,  the  older  biotite-rhyolite  frequently  comes  to  the 
surface  and  is  distinguishable  by  its  more  rugged  topograj)hy. 

RELATIVE   AGE   OF   IGNEOUS   ROCKS. 

In  the  section  at  Twin  Springs  it  is  shown  that  the  rhj^olite  is  older 
than  the  basalt.  Between  Twin  Springs  and  Reveille  the  intervening 
series  of  tuffs  disappears  with  increasing  elevation,  and  the  basalt 
mantles  around  the  base  of  craggy  rhyolite  eminences  in  sucli  a  way 
as  to  show  that  they  were  already  mountaius  before  the  basalt 
appeared.  The  disappearance  of  the  intervening  tuffs  also  suggests 
that  the  higher  rhyolite  ijeaks  Avere  mountains  in  the  lakes  in  which 
the  rhyolitic  tuffs  were  laid  down. 

ORE   DEPOSITS. 

In  the  vicinity  of  Reveille  are  mines  which  formerl}^  were  very 
profitable,  but  which  are  now  almost  entirely  deserted.  The  mines 
are  situated  in  a  patch  of  limestone  and  quartzite  surrounded  by 
volcanic  rocks,  and  the  ores  probably  have  genetic  connection  with 
the  dikes  which  traverse  the  sedimentaries. 

I 

^'  BELTED    RANGE. 

The  Belted  Range  runs  southward  from  the  Reveille  Range  and 
forms,  in  its  southern  part,  the  eastern  boundary  of  the  Aniargosa 
Desert.  It  is  somewhat  irregular,  but  has  a  general  north-south 
trend.  At  its  northern  end  it  is  separated  from  the  Reveille  Range 
by  a  slight  interval  of  low,  lava-covered  country,  while  at  its  south 
end  it  is  separated  from  the  low  mountains  Ijing  north  of  Pahrump 
Valley  by  a  considerable  intervening  area  of  Pleistocene  subaerial 
deposits.  Its  name  has  probably  been  given  to  it  on  account  of  the 
horizontal  banding  visible  for  a  long  distance  on  its  steep  sides. 


\ 


164  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH   PARALLEL,     [bull.208. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

The  Belted  Range  was  crossed  by  Mr.  Gilbert  during  his  recon- 
naissance for  the  AVheeler  survey.  He  notes  that  at  White  BlufE 
Spring  and  for  several  miles  southward  the  range  shows  an  axis  of 
quartzite.*^  This  he  regards  as  the  same  formation  as  a  similar 
quartzite  recognized  in  the  Timpahute  Range,  which  is  of  Cambrian 
age. 

The  whole  southern  portion  of  the  range,  as  seen  from  the  south,  is  : 
of  stratified  rocks,  apparently  chiefly  limestones.  It  is  probable  that 
this  portion  of  the  range  forms  a  part  of  the  general  Cambrian- 
Silurian  area,  which  includes  part  of  the  northern  end  of  the  Spring 
Mountain  Range,  a  large  portion  of  Las  Vegas  Range,  and  at  least 
the  southern  end  of  the  Desert  Range. 

IGNEOUS  ROCKS. 
VOLCANIC   ROCKS. 

Mr.  Gilbert^  found  that  near  White  Bluff  Spring  the  principal  mass 
of  the  range  was  of  lavas,  which  nearl}^  hid  the  Paleozoic  axis.  These 
lavas  stretch  northeastward  and  connect  with  those  of  the  Reveille 
Range,  and  also  extend  westward,  forming  low  mountains,  which 
divide  the  Ralston  Desert  from  the  Amargosa  Desert.  In  these 
mountains  Fortymile  Canyon  is  cut.  They  extend  westward  at  least 
as  far  as  Oasis  Vallej^,  which  is  the  head  of  the  Amargosa  River ;  and 
they  stretch  northward  over  the  whole  of  the  Ralston  Desert. <^ 

STRUCTURE. 

The  probable  structure  of  the  Paleozoic  southern  portion  of  the 
range  could  only  be  uncertainly  made  out  from  a  distant  view.  In 
general,  however,  the  rocks  appear  nearly  horizontal,  but  they  some- 
times dip  as  much  as  15°  at  least.  The  general  strike  is  i^arallel  with 
the  trend  of  the  range. 

SPRING  MOUNTAIN   RANGE. 

The  Spring  Mountain  Rauge  is  an  exceedingly  irregular-shaped 
group  of  mountains,  lying  southwest  of  Las  Vegas  Range,  and  sepa- 
rated from  the  Kingston  Range,  farther  south,  by  the  Pahrump 
Valley.  The  general  trend  of  the  range  is  northwest  and  southeast, 
and  its  length  in  this  direction  is  about  60  miles,  and  at  its  northern 
end,  in  the  neighborhood  of  Charleston  Peak,  the  total  width  is  as 
much  as  30  miles.  This  peak  constitutes  the  highest  portion  of  the 
range,  being  10,874  feet  above  the  sea,  and  is  a  conspicuous  landmark. 
This  range  is  divided  into  numerous  ridges,  which  run  in  many  dif- 

a U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer,,  Vol.  Ill,  p.  123.  » Ibid.  c  See  p.  182. 


SPURR]  SPRING    MOUNTAIN    RANGE.  165 

ferent  directions  without  much  visible  system.  At  at  least  two  points 
at  the  northern  base  of  the  range  there  occur  warm  springs,  namely, 
Indian  Spring  and  the  spring  at  White's  ranch  in  Pahrnmp  Valley 
This  is  interesting,  since  the  range  contains  few  igneous  rocks. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

The  north  end  of  the  range  was  traversed  from  Indian  Spring 
southwest,  b}^  way  of  Hornet  Spring,  to  White's  ranch.  At  Indian 
Spring  are  limestones  carrying  Lower  Carboniferous  fossils,  as  deter- 
mined by  Dr.  Girty.  Following  up  the  canyon  which  leads  southward 
to  Hornet  Spring  a  great  thickness  of  limestones  was  passed  through, 
all  striking  a  little  north  of  east,  parallel  in  general  with  the  north 
end  of  the  range,  and  dipping  northward  at  angles  varying  from  20° 
to  65°.  The  limestone  is  all  thin  bedded.  North  of  the  summit  of 
the  pass  comes  in  a  thin  bed  of  vitreous  quartzite.  At  the  summit 
is  a  thick  white  vitreous  quartzite,  often  coarse  and  nearly  conglom- 
erate, beneath  the  limestone.  Just  south  of  the  summit  there  is  an 
east- west  fault  which  cuts  off  the  quartzite  and  again  brings  down 
the  limestone  into  the  section.  In  this  limestone,  at  a  point  half  a 
mile  south  of  Hornet  Spring,  were  found  abundant  fossils,  which 
have  been  determined  by  Mr.  Walcott  to  be  Cambrian,  probably 
Middle  Cambrian.  These  fossils  are  in  blue-gray  semicrystalline 
limestone  like  that  found  above  the  quartzite  north  of  the  fault.  It 
is  probable,  therefore,  that  some  of  the  limestones  exposed  in  ascend- 
ing the  canyon  north  of  the  summit  belong  to  the  Cambrian,  and  that 
these  pass  upward  into  the  Lower  Carboniferous  limestones  at  Indian 
Spring  without  any  marked  stratigraphic  or  lithologic  break.  The 
white  quartzite  at  the  summit  is  also  probably  Cambrian,  since  it 
underlies  the  limestones. 

The  thickness  of  the  section  shown  north  of  the  fault  has  been 
estimated  at  about  17,000  feet,  of  which  an  estimated  thickness  of 
2,000  feet  ma}'  be  taken  for  the  quartzite,  leaving  15,000  feet  for  the 
limestones. 

The  Cambrian  limestones  near  Hornet  Spring  are  continuous  only 
a  short  distance  south,  when  they  give  place  abruptly  to  Carbonif- 
erous limestones,  the  two  being  apparentlj^  separated  by  an  east- west 
fault,  parallel  with  and  only  some  3  miles  south  of  the  one  already 
mentioned.  From  this  j)oint  to  the  southern  end  of  the  range  it  is 
probable  that  no  Cambrian  rocks  are  exposed,  since  Carboniferous 
fossils  are  found  at  many  points. 

Mr.  R.  B.  Rowe's  notes'*  on  the  Cambrian  may  be  summarized  as 
follows : 

About  7  miles  south  of  Indian  Spring,  in  a  high  range  of  hills, 
were  found  greenish-yellow  shales,  with  thin,  dark  sandstone  bands 


a  Made  in  1900-1901.    Taken  from  his  notebooks,  after  his  death,  by  the  writer. 


166  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 308. 

containing  trilobite  and  linguloid  shells.     These  were  nnderlaiu  by 
brownish  massive  limestone,  containing  great  numbers  of  trilobite 
remains.     These   Cambrian  rocks  appear  to  be  directly  overlain  by 
dark-bine  and  gray,  iDrobably  Carboniferous,  limestones.     The  dip  of  \ 
the  Cambrian  rocks  is  due  north,  while  that  of  the  Carboniferous  is  to  \ 
the  south,  suggesting  an  unconformity,,  although  the  two  formations 
are  divided  b}^  a  covered  wash  2^  miles  Avide.     The  Cambrian  may  be  I 
separated  from  the  Carboniferous  here  hy  a  fault  or  bj^  an  uncon- 
formit3^ 

In  the  whole  Spring  Mountain  Range  nothing  was  found  between 
the  Cambrian  and  the  Carboniferous  suggesting  a  hiatus  between  the 
two  periods. 

On  the  southwest  side  of  a  traversed  line  from  Indian  Creek  to  Tule 
Springs  (on  the  east  side  of  Las  Vegas  Range),  from  a  distance 
about  5  miles  east  of  Indian  Creek  to  about  5  miles  west  of  Corni 
Creek,  the  low  hills  near  the  valley  are  Cambrian,  and  probablj^  some 
on  the  north  side  of  the  valley  also.  About  6  or  7  miles  southwest  of 
Corn  Creek,  on  the  south  side  of  the  valley,  there  is  apparently  a 
fault,  bringing  the  Cambrian  against  what  is  i:)robabl3'  the  Carbon-i 
iferous  (fig.  22).  The  Cambrian  comprises  a  number  of  parallel 
ridges,  with  steep  south-facing  escarpments  and  with  strata  dii^ping; 
north.     Between  the  ridges  is  a  covering  of  talus. 

CARBONIFEROUS. 

At  Indian  Spring  Lower  Carboniferous  fossils  were  found  in  a  black, 
fetid,  semicrystalline  limestone  with  brown  sandy  beds.  They  were 
determined  bj'^  Dr.  Girty  as  follows: 

Ptilodictya  sp. 
Chonetes  sp. 
ProchictiTS  cf.  mesialis. 
Orthothetes  11.  8p. 

Dr.  Girt}^  remarks  that  this  fauna  can  not  with  certainty  be  placed* 
in  the  Lower  Carboniferous,  though  it  is  probably  of  that  age. 

These  rocks  probably  constitute  a  relativel}'^  narrow  strij^  at  the 
northern  end  of  the  range,  and  are  succeeded  on  the  south  by  older 
strata,  as  above  described. 

A  few  hundred  yards  south  of  the  ranch  at  Indian  Spring  the  fol- 
lowing Carboniferous  fossils  were  collected  by  Mr.  F.  B.  Weeks,  in 
1900,"  and  were  determined  by  Dr.  Girty: 

Zaphrentis  sp.  Productns  cf.  P.  Isevicosta. 

Rliipidomella  oweni.  Spmfer  keokiik. 

Orthothetes  insequalis.  Spirifer  near  neglectiis. 

Prodnctella  concentrica  ?  Seminnla  liumilis. 

Prodiictns  btirlingtonensis.  Camarotoechia  sp. 
Productus  semireticiilatus. 

a  Personal  communication  to  the  writer. 


SPURK.]  SPRING    MOUNTAIN    RANGE.  167 

At  the  same  locality  Mr.  R.  B.  Rowe'*  noted  and  collected  Lower 
C'arboniferons  fossils.  The  rock  is  massive  and  chert}' blue  and  gray 
limestone,  with  reddish  and  yellowish  shalj^  and  arenaceous  laj^ers. 
The  section  is  as  follows  from  the  top  downward: 

Section  near  Indian  Sjrrings. 

1.  Massive  clierty  blue  limestone,  poor  in  fossils.     Thickness  unknown. 
Unconformity. 

2.  Red  shales  with  thin  bands  of  blue  limestone  and  yellowish  calcareous  sand- 

stone, about  300  feet.     Lower  Carboniferous  fossils. 

3.  Massive  blue  limestone  filled  with  crinoids  and  corals.     Thickness  unknown. 

Fossils  collected  from  the  red  shales  underlying  the  upper  blue 
limestone  unconformabh^  were  determined  by  Dr.  Girty  to  be  Upper 
Carboniferous  or  Pennsylvanian,  rather  than  Lower  Carboniferous. 
Therefore  the  line  between  LTpper  and  Lower  Carboniferous  lies 
between  2  and  3. 

About  half  a  mile  south  of  Indian  Creek,  fossils  collected  by  Mr. 
Rowe  from  the  rocks  that  apparently  underlie  Ihe  red  beds  from 
which  the  LTpper  Carboniferous  fossils  were  taken,  were  found  by 
Dr.  Girty  to  be  Lower  Carboniferons  or  Mississippian. 

About  7  miles  south  of  Indian  Creek,  the  fol'owing  Carboniferous 
section  was  found  by  Mr.  Rowe,  overlying  the  Cambrian.  The  sec- 
tion is  given  from  the  toj:*  down. 

Section  7  miles  south  of  Indian  Creek. 

1.  Massive  dark-blue  limestone,  weathering  rough,  and  containing  white  calcite 

spots. 

2.  Light-gray,  massive,  unfossiliferous  limestone. 

3.  Massive  dark-blue  limestone,  like  No.  1. 

About  3  or  4  miles  south  of  Hornet  Spring  fossils  are  found  in  yellow- 
weathering,  blue,  slialy,  argillaceous,  cherty  limestone,  which  lies  to 
the  south  of  the  thin-bedded  Cambrian  limestone,  and  is  not  readily 
separable  from  it  in  the  field.  In  this  yellowish,  shaly  limestone 
Fusidina  cylindrica  was  found,  and  the  liorizon  was  therefore  deter- 
mined by  Di".  Girty  as  Upper  Ca-boniferous.  Southward  from  here, 
as  far  as  the  jDoint  where  the  road  enters  the  foothills,  tlie  ]"ocks  are 
all  similar  thin-bedded  limestones. 

To  the  east,  Charleston  Peak  and  the  high  ridge  south  of  it  are 
formed  of  massive  limestone,  which  has  all  the  appearance  of  belong- 
ing to  the  great  Carboniferous  series.  Mr.  Turner  has  informed  the 
writer  that  Carboniferous  fossils  have  actually  been  found  on  Charles- 
ton Peak  by  surveyors. 

On  the  east  side  of  Charleston  Canyon  Mr.  Rowe*  noted  that  the 
range  seemed  to  be  made  ux3  of  Carboniferous  limestone.  Well  down 
in  these  strata  some  fossils  were  found,  chiefly  Fusulina.  The  rocks 
are  light-gray  arenaceous  limestones,  containing  considerabk^  chert. 


a  Taken  from  Mr.  Rowe's  notebooks  of  1900  and  1901,  after  his  death,  by  the  writer. 
b  Notebooks.    See  above. 


1G8  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 


Fossils  collected  by  Mr.  Rowe  were  identified  hy  Dr.  Girty  as  Peuu- 
sylvauian  oi-  Upper  Carboniferous. 

la  the  foothills  of  the  range,  just  east  of  White's  ranch,  in  Pahrump 
Valley,  a  collection  of  Lower  Carboniferous  fossils  was  obtained,  as 
determined  by  Dr.  Girty: 

Zaphrentis  sp.  Spiriferina  sp. 

Aulopora  sp.  Atliyris  lamellosa. 

Fenestella  sp.  Seminula  sp. 

Leptsena  I'homboidalis.  Rhynclionella  sp. 

Chonetes  planumbontis  ?  Beyricliia  sp. 

Productus  cf.  mesialis.  Phillipsia  sp. 
Spirifer  cf .  grimesi. 

About  7  miles  north  of  the  above  locality  the  rocks  are  also  Carbon- 
iferous, according-  to  a  note  supplied  b}^  Mr.  Turner.  Fossils  were 
collected  bj^  Mr.  F.  C.  Boyce  from  near  Fremont  Wash,  7^  miles 
north-northeast  of  Manse  post-office  (White's  ranch).  On  these  Mr. 
Schuchert,  of  the  United  States  National  Museum,  reported: 

The  fossils  *  *  *  are  of  Carboniferous  age.  There  are  two  species  of  Za- 
phrentis, a  Syringopora  near  multaticnuata  and  a  Spirifer  fragment  too  small  for 
determination. 

South  of  Manse  the  range  was  not  visited  by  the  writer,  but  he 
observed  that  the  same  series  of  rocks  extended  east  and  soutli  for  a 
number  of  miles.  Mr.  Gilbert,  however,  observed  Carboniferous  rocks 
east  and  south  of  here,  at  Cottonwood  Spring^  and  at  Olcott  Peak.^ 
At  the  first-named  locality  Mr.  Gilbert  made  the  following  section: 

Section  at  Cottomcood  Spring. 

Feet. 
1.  Massive  red  and  yellow  sandstone: 

a.  Yellow,  250  feet 1 

h.  Red,  150  feet ". |  „ 

c.  Yellow,  200  feet '      ' 


II 


d.  Red  and  shaly,  400  feet 

2.  Bedded,  fine-grained  to  saccharoid  limestone,  gray  and  cream-colored: 
beds  separated  by  shaly  layers  so  as  to  weather  in  steps.  [Phillipsia 
(?) ,  Macrocheihts  (non  des.),  Naticopsis,  Aviculopecten,  Avicida,  Meek- 
ella,  Myalina,  Productus  semiretieulatiis,  Spirifer  lineatus,  Athyris 

suhtilita,  Synocladia] 500 

S.  Massive  gypsum,  white  and  red,  in  lenticular  masses 0  to  70 

4.  Gray,  massive,  cherty  limestone: 

a.  Jjivaestone  [Meekella,  Productus,  CticeteteSjSyiHngojyora], 250  feet  A 

b.  Unseen;  red  (shale  ?) ,  25  feet. .  _ : \        475 

c.  Limestone,  200  feet . J 

5.  Friable  sandstone,  in  places  shaly  or  marly;  variegated  with  brilliant 

iron  colors 350 


Total _.   ^ 2,395 

The  fossils  here  show  that  the  rocks  of  the  section  are  Upper  Car- 
boniferous. At  Olcott  Peak  the  fossils,  according  to  Mr.  Gilbert,  are 
Lower  Carboniferous. 


aU.  S.  Geog.  Surv.  W  One  Hundredth  Mer.,  Vol.  Ill,  p.  166.  61bid.,  p.  32. 


SPURR.]  SPRING    MOUNTAIN    RANGE.  169 

At  Mountain  Spring,  a  point  about  G  miles  west  of  Cottonwood 
Spring,  Mr.  Gilbert"  notes  that  Mr.  C.  A.  Ogden  obtained  a  set  of 
fossils  of  facies  older  than  the  Coal  Measures.  Among  the  forms  are 
PMUi2:)sia,  82:)irifer  (two  species  of  Devonian  aspect),  RhynchoneUa, 
Hemipronites,  Afhyn's  (distinct  from  A.  suhtilita),  Choneies,  Tere- 
hratula  (.^),  Productus  (like  P.  subacideatus),  and  FenesteUa.  The 
horizon  is  referred  to  the  Lower  Carboniferous. 

The  following  valuable  observations  on  the  Carboniferous  of  the 
southern  portion  of  the  Spring  Mountain  Range  were  made  bj^  Mr. 
R.  B.  Rowe  in  1900-1901:* 

Lower  Carboniferous. — About  6  miles  south  of  Good  Spring,  Lower 
Carboniferous  limestones  are  found,  probably  separated  by  an  over- 
thrust  fault  from  Mesozoic  strata.  The  Carboniferous  is  much  altered, 
but  in  some  of  the  layers  good  corals  are  found.  The  Mesozoic  beds 
consist  of  rich  shales  and  sandstones. 

At  Mountain  Spring  fossil-bearing  Lower  Carboniferous  beds  not 
more  than  3,000  feet  thick  occur.  Above  these  are  Carboniferous  red 
beds,  at  least  2,000  feet  thick,  which  are  overlain  by  Upper  Carbon- 
iferous limestone,  from  500  to  600  feet  thick.  Beneath  the  Lower  Car- 
boniferous is  a  light-graj^  arenaceous  limestone.  The  line  between 
this  limestone  and  the  overljang  Carboniferous  limestone  is  sharply 
drawn.  *" 

Carboniferous  red  beds  {Upper  Carboniferous). — About  one-half 
mile  west  of  Mountain  Spring,  on  the  road  to  Mule  Spring,  is  a  dark 
fossiliferous  limestone  lying  upon  a  light-colored,  much-altered  lime- 
stone. These  limestones  are  ijrobably  Lower  Carboniferous.  In  the 
vallej^  west  of  Mountain  Spring  they  are  overlain  \)y  a  considerable 
thickness  (2,000  feet?)  of  red  Carboniferous  shales  and  sandstones, 
which  form  a  greater  portion  of  the  Mule  Spring  Mountains  and  are 
capped  by  the  Upper  Carboniferous  fossil-bearing  cherty  limestones. 
On  the  east  side  of  Mule  Spring  Mountain  the  red  shales  and  sand- 
stones are  found  at  the  base,  capped  b}^  the  Upper  Carboniferous 
limestones. 

For  8  or  10  miles  north  and  northwest  of  Mule  Spring  the  Upper 
Carboniferous  is  overlain  hy  the  fossiliferous  Jurassic. '^^  There  are 
no  red  beds  or  conglomerates  between  the  two  formations,  although 
some  of  the  topmost  layers  of  the  Carboniferous  are  conglomeratic. 
The  thickness  of  the  Upper  Carboniferous  limestone  is  about  500  feet. 
The  thickness  of  the  Upper  Carboniferous  red  shales  and  sandstones 
exposed  in  this  region  must  be  two  or  three  times  as  much. 

Between  Mule  Spring  and  Mountain  Spring  red  sandstone  occurs, 
with  a  northerly  strike  and  a  dip  20°  west. 

At  Mountain  Spring  the  Carboniferous  red  beds  lying  above  the 

all.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  HI.,  p.  180. 

6  Taken  from  his  notebooks,  after  his  death,  by  the  writer. 

c  See  citation  from  Mr.  Gilbert  on  region  of  Mountain  Spring,  above. 

d  Mr.  Rowe's  field  determination. 


170  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL.     Lbull.308. 

Lower  Carboniferous  are  at  least  2,000  feet  thick,  and  are  overlain   i 
by  500  to  600  feet  of  Upper  Carboniferous  limestone. 

On  a  divide  along  the  road  between  Good  Spring  and  Cottonwood 
Spring,  Carboniferous  red  beds  immediately  underlie  the  fossilifer- 
ous  Jurassic,'^  as  is  the  case  also  at  Good  Spring;  but  about  G  miles 
east  of  Cottonwood  Spring  the  Jurassic'^  lies  directly  upon  the  Upper  j 
Carboniferous  limestone. 

South  of  Indian  Spring,  at  the  northern  end  of  the  range,  are  red 
shales  and  sandstones  underlying  massive  blue  limestones  uncon- 
formably.  The  shaly  layers  and  the  thin  limestone  bands  in  these 
red  beds  are  fossiliferons.  They  were  determined  by  Dr.  Girty 
as  Upper  Carboniferous.  The  formation  here  has  a  thickness  of 
about  300  feet.  It  overlies  blue  massive  Lower  Carboniferous  lime- 
stone. 

U'pyer  Carboniferous  limestone.— For  8  or  10  miles  north  and  noi'th- 
west  of  Mule  Spring  the  folded  Upper  Carboniferous  is  overlain  by 
fossiliferons  Jurassic.  "  The  Upper  Carboniferous  limestone  is  about 
500  feet  tliick ;  the  Upper  Carboniferous  red  shales  and  sandstones 
about  2,000  feet  thick.  The  Upper  Carboniferous  limestone  maj^  be 
divided  about  equally  into  (1)  upper  clierty  massive  limestone,  con- 
taining abundant  fossils;  (2)  lower  light-gray,  massive  limestone, 
containing  a  few  fossils.  The  two  portions  are  divided  in  some  i^laces 
by  layers  of  red  shales  and  sandstones,  as,  for  example,  at  Cotton- 
wood Spring.  One-half  mile  west  of  Mule  Spring  Mr.  Rowe  col- 
lected fossils  determined  by  Dr.  Girtj^  as  Pennsylvanian  or  LTpper 
Carboniferous. 

On  the  escarpment  of  the  west  side  of  the  Mule  Sj)ring  Mountain 
there  is  exposed  the  Upper  Carboniferous  limestone,  underlain  by  the 
red  shale  formation. 

At  Mountain  Spring,  Cai'boniferous  red  beds  are  at  least  2,000  feet 
thick.  They  overlie  about  3,000  feet  of  Lower  Carboniferous  strata, 
and  underlie  Upper  Carboniferous  limestone  from  500  to  600  feet  thick. 
Beneath  the  Lower  Carboniferous  is  a  light-graj^  arenaceous  limestone, 
containing  no  discovered  fossils. 

At  Cottonwood  Spring  fossils  were  collected  from  the  Upper  Car- 
boniferous by  Mr.  Rowe,  and  were  subsequently  identified  as  such  by 
Dr.  Girty.*  Upper  JCarboniferous  beds  were  followed  [some  distance 
south  of  Cottonwood  Spring ;  also  east  of  Cottonwood  Spring. 

In  the  hills  north  and  northwest  of  Cottonwood  Spring  the  Upper 
Carboniferous  is  overlain  by  conglomerate  and  strongly  cross-bedded 
coarse  sandstone,  in  beds  10  or  20  feet  thick.  Above  these  conglom- 
erates are  shales  and  gypsum  beds,  above  which  again  are  the  fossil- 
iferous  arenaceous  Jurassic"  limestones. 

a  Mr.  Rowe's  field  determination. 

''See  citation  from  Mr.  Gilbert  on  Upper  Carboniferous  at  Cottonwood  Spring,  above. 

^  Mr.  Rowe's  field  determination. 


SPURR]  SPRING    MOUNTAIN    RANGE.  171 

About  3  miles  southeast  of  tlie  summit,  between  Good  Spring  and 
A\"ilson's  ranch,  the  Lower  Carboniferous  of  the  Bird  Spiring  Range 
lies  against  the  Upper  Carboniferous  and  Jurassic,'^  being  separated 
l)y  a  fault. 

About  6  miles  east  of  Cottonwood  Spring,  directly  overlooking  Las 
^'egas  Valley,  is  an  escarpment  consisting  of  Upper  Carboniferous 
beds.  These  are  underlain  bj^  lieavj^  shales  and  brownish  micaceous 
sandstone,  much  cross-bedded.  At  this  point  the  red  beds  seen  are 
not  over  50  feet  thick. 

Between  Good  Spring  and  Cottonwood  Spring  the  Upper  Carbon- 
iferous repeatedlj^  occurs.  North  of  Good  Spring  a  low  knoll  of  the 
Upper  Carboniferous  occurs  west  of  the  road,  up  to  the  Mesozoic 
cliff  at  the  foot  of  Oleott  Peak  (Potosi  Mountain).  Near  the  summit 
both  Carboniferous  and  Mesozoic  rocks  occur  along  the  road.  East 
and  north  of  Cottonwood  Spring  are  apparentl}^  Carboniferous  rocks, 
while  south  and  west  are  Mesozoic. 

About  12  miles  north  of  Good  Spring,  near  the  divide  between  Good 
Spring  and  Cottonwood  Spring,  is  a  small  area  of  Upper  Carbonifer- 
ous, occupying  a  fault  zone  which  s^^arates  the  probably  Mesozoic 
red  sandstones  and  shales  from  the  Lower  Carboniferous  limestones 
which  make  up  Oleott  Peak.*  On  the  east  side  of  Oleott  Peak, 
about  10  miles  north  of  Good  Spring,  fossils  were  collected  by  Mr. 
Rowe  that  were  identified  b}'  Dr.  Girty  as  Upper  Carboniferous  or 
Pennsylvanian . 

About  3  miles  northeast  of  Good  Spring,  in  the  Bird  Spring  Moun- 
tains, there  was  noted  about  425  feet  of  gray,  brownish,  and  pinkish 
arenaceous  limestone.  Fossils  collected  at  three  different  horizons  in 
the  series  bj^  Mr.  Rowe  were  determined  by  Dr.  Girty  to  be  Upper 
Carboniferous  or  Pennsylvanian. 

At  Good  Sj)ring  the  following  section  was  obtained,  from  the  top 
down : 

Section  at  Good  Spring. 

Consolidated  ancient  tains 6-10 

Arenaceous  light-brown  limestone,  rather  thin  bedded 610 

In  part  yellowish  and  reddish  shales  and  sandstones,  which  make  the  same 

red  terrane  as  shown  at  the  eastern  base  of  Oleott  Peak 760 

Heavy  conglomerate,  siibangular  pebbles 50 

Gray  limestone  with  some  red  and  pinkish  arenaceous  layers  and  cherty 
layers:  the  tipper  50  feet  is  conglomeratic  and  contains  large  qiiartzite 
bowlders:  fossils  abundant  in  the  conglomerate,  less  so  in  the  rest 300 

Mr.  Rowe  regards  the  50  feet  of  conglomerate  underlying  the  red 
beds  as  a  basal  conglomerate,  and  the  conglomerate  at  the  top  of  the 
limestone  beneath  as  an  apical  conglomerate.  Fossils  of  the  lower 
conglomerate  collected  by  Mr.  Rowe  are  regarded  hx  Dr.  GiYij  as 
probably  Permian,   or  uppermost  Carboniferous.      Fossils  collected 

«  Mr.  Rowe's  field  determination. 

&See  citation  from  Mr.  Gilbert  on  Lower  Carboniferous  at  Oleott  Peak,  above. 


172  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH   PARALLEL,     [bull.208. 

from  the  arenaceous  limestone  overlying  the  red  beds  are  regarded  by 
Dr.  T.  W.  Stanton  as  not  younger  than  Trias,  and  perhaps  as  old  as 
the  Permian. 

Fossils  collected  from  the  Upper  Carboniferous  at  Cottonwood 
Spring  by  Mr.  Rowe  are  regarded  as  possibly  Permian  by  Dr.  Girt3^ 

East  and  southeast  of  Good  Spring,  along  the  road  to  Manvel, 
occurs  the  contact  of  the  Mesozoic  and  Carboniferous.  On  the  east 
and  north  are  Upper  Carboniferous  beds  with  fossils  identical  with 
those  found  at  Good  Spring.  The  red  shales,  sandstones,  and  con- 
glomerates which  He  between  the  Upper  Carboniferous  and  Jurassic 
at  Good  Spring  and  at  Olcott  Peak  are  wanting  about  5  miles  south- 
east of  Good  Spring,  and  the  calcareous  sandstones  of  the  Jurassic 
lie  directly  upon  the  Carboniferous.  The  Upper  Carboniferous  also 
has  lost  at  this  point  the  conglomerate  which  lies  at  its  top  at  Good 
Spring. 

The  mountains  near  Good  Spring  are  chiefly  limestones,  with  con- 
siderable sandstone  underlying.  Fossils  collected  by  Mr.  Rowe  from 
the  lowest  rocks  exposed  in  the  Bird  Spring  Range"  were  identified 
by  Dr.  Girty  as  Pennsylvanian.  or  Upper  Carboniferous. 

Correlation  ivith  Grcmd  Canyon  section. — In  the  Grand  Canj^on  and 
Colorado  Plateau  region  the  Carboniferous  was  studied  in  the  course 
of  the  Wheeler  survey  by  Messrs.  Gilbert  and  Marvine.  It  was 
divided  into  the  Aubrey  limestone,  the  Aubrey  sandstones,  and  the  Red 
Wall  limestone.  The  Aubrey  limestone  has  a  maximum  thickness  of 
820  feet,  and  contains  fossils  suggesting  the  Permo-Carboniferous  of 
the  Mississippi  Vallej^,  and  indicating  the  close  of  the  Carboniferous 
age.  The  limestone  is  characterized  by  a  great  abundance  of  chert, 
which  toward  the  top  sometimes  constitutes  half  the  mass.  Near  the 
middle  it  is  in  some  places  interrupted  by  a  bed  of  shale  with  gypsum. 

The  Aubrey  sandstone  has  a  thickness  along  the  Grand  Canyon  of 
about  1,000  feet.  A  portion  is  massive  and  cross-bedded,  another 
portion  soft  and  gypsiferous.  The  sandstones  contain  no  fossils,  but 
an  intercalated  limestone  bears  Coal  Measures  shells. 

The  Red  Wall  limestone  has  a  gray  color  on  fresh  fracture.  It  is 
heavy-bedded  and  massive.  Near  the  top  sandstone  alternates  with 
the  limestone  for  from  200  to  500  feet.  Tiirough  its  lower  half  the 
limestone  is  interrupted  by  occasional  shaly  bands.  The  average 
total  thickness  is  2,500  feet.  Fossils  are  abundant  near  the  top,  but 
in  the  lower  portions  are  difficult  to  find.  The  lowest  fossils  were 
found  a  little  below  the  middle  of  the  series,  and  were  doubtfully 
referred  to  the  Lower  Carboniferous.  The  fauna  of  the  upper  portion 
is  rich,  and,  while  different  from  that  of  the  Aubrey  limestone,  is 
referable  to  the  Coal  Measures. 

Mr.  Gilbert  ^  was  not  able  to  exactly  correlate  the  Colorado  Plateau 

«  The  southern  prolongation  of  the  Spring  Mountain  Range,  lying  east  of  Good  Spring. 
b  U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer  ,  Vol.  Ill,  pp.  177, 178, 179. 


SPURR.]  SPRING    MOUNTAIN    RANGE.  173 

and  Grand  Canyon  Carboniferous  witli  the  Carboniferous  series  in 
the  Spring  Mountain  Range.  Nevertlieless,  the  Carboniferous  de- 
scribed by  Mr.  Rowe  seems  to  bear  a  general  resemblance  to  the 
Colorado  Plateau  and  Grand  Canj^on  section.  This  correlation  may 
be  suggested : 

Correlation  of  Spring  Mountai)i  coid  Grand  Canyon  sections. 


Gilbert  and  Marvine,  Grand  Canyon  section. 


RoXve,  Spring  Mountain  section. 


Aubrey  limestone,  maximum  830  feet,  Upper     Upper  Carboniferous  limestone,  500-600  feet. 
Carb'oniferoiis. 

Aubi'ey  sandstone,  l.(XXl  feet,  probably  Upper     Carboniferous  red  sandstone,  shale,  and  con- 
Carboniferous,  glomerate,  1,000-2,000  feet,  probably  Upper 

I      Carboniferous. 

Red  "Wall  limestone,  Upper  and  Lower  Carbon-  '  Lower  Carboniferous  limestones,  3,000  feet, 
iferous,  3,500  feet.  [ 


MESOZOIC. 

Eight  or  10  miles  north  and  northwest  of  Mule  Spring  the  Upper 
Carboniferous  is  overlain  by  fossiliferous  Jurassic.^  Among  the  fos- 
sils seen  in  the  Jurassic  Pentacrinus  astericus"'  is  very  abundant. 

About  4  miles  west  of  Cottonwood  Spring  is  a  great  escarpment,  at 
least  2,000  feet  high.  It  consists  of  two  terranes,  the  lower  being  red 
shales  and  sandstones,  making  up  about  one-third  of  the  height. 
Above  this  is  a  heavj^  yellow  sandstone,  containing  occasional  red 
lenses.     These  rocks  are  probably  Mesozoic. 

To  the  east  and  northeast  of  Cottonw^ood  Spring  the  hills  appear 
to  be  Mesozoic  also. 

In  the  hills  north  and  northwest  of  Cottonwood  Spring  the  Upper 
Carboniferous  is  overlain  by  beds  of  conglomerate  and  coarse,  strongly 
cross-bedded  sandstone.  These  beds  are  from  10  to  20  feet  thick. 
Overlying  these  conglomerates  are  100  feet  or  more  of  intercalated 
white  gj-psum  beds  and  red  shales,  and  above  these  lies  the  fossil- 
iferous arenaceous  limestone  of  the  Jurassic.'*  Near  the  bottom  of  the 
fossiliferous  beds  is  a  stratum  containing  a  multitude  of  Gryphoea/'' 

About  10  miles  north  of  Wilson's  ranch,  the  Carboniferous  lime- 
stone has  been  brought  above  massive  red  Mesozoic  sandstone  by  a 
great  overthrust  fault.  Between  Wilson's  i-anch  and  Red  Spring  the 
Mesozoic  is  also  found.  About  8  or  10  miles  north  of  Wilson's  ranch 
the  same  overthrust  fault  as  mentioned  above  was  found.  The  mas- 
sive Mesozoic  sandstone  here  is  colored  pink,  bright  vermilion  red, 
and  white.     It  is  strongly  cross  bedded  everywhere. 

Between  Wilson's  ranch  and  Cottonwood  Si)ring  the  low  hills  show 
strata  which  contain  Jurassic  fossils. 

About  three-quarters  of  a  mile  south  of  the  summit,  between  Good 
Spring  and  Wilson's  ranch,  the  Jurassic  lies  at  the  foot  of  a  ridge 
made  up  of  Upper  Carboniferous  rocks,  the  Carboniferous  being  sepa- 
rated from  the  Mesozoic  by  a  fault. 

a  Mr.  Rowe's  field  determination. 


174  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH    PARALLEL,     [btjll.308. 

At  the  foot  of  Olcott  Peak  there  is  a  cliff  composed  of  Mesozoic 
rocks.  From  here  the  Mesozoic  turns  east  aud  crosses  the  road  before 
the  summit  between  Good  Spring  and  Cottonwood  Spring  is  reached. 
Near  the  summit  Carboniferous  and  Mesozoic  alternate  along  the 
road.  From  the  summit  to  Cottonwood  Spring,  Mesozoic  rocks  occur 
on  both  sides  of  the  road.  The  rocks  in  the  hills  south  and  west  of 
Cottonwood  Spring  are  Mesozoic. 

On  the  great  fault  line  which  separates  the  Mesozoic  from  the 
Carboniferous  between  Good  Spring  and  Cottonwood  Spring,  the 
fossiliferous  Jurassic  apparently  lies  beneath  the  red  and  white  sand- 
stones which  form  the  cliffs  west  of  Wilson's  ranch. 

At  Good  Spring  the  Mesozoic  was  found  overlying  the  Carbonifer- 
ous.    The  following  is  the  section  : 

Section  of  Mesozoic  at  Good  Spring. 

Feet. 

1.  Arenaceous  limestone 610 

2.  At  base  yellowish  and  reddish  sandstone  about  50  feet  thick.     Above  this 

are  layers  of  red  and  yellowish  shale.     This  may  be  the  same  red  terrane 
which  shows  at  the  eastern  base  of  Olcott  Peak 760 

3.  Heavy  conglomerate 50 

4.  Gray  limestone,  with  some  layers  of  red  or  pinkish  arenaceoiis  limestone, 

and  abimdant  layers  of  chert.     The  upper  50  feet  contains  numerous 
large  quartzite  bowlders . 300 

Fossils  collected  from  No.  1  were  described,  after  a  preliminary 
examination  by  Mr.  T.  W.  Stanton,  as  belonging  to  a  horizon  not 
younger  than  the  Triassic,  and  possibly  as  old  as  the  Permian.  The 
fossils  collected  from  No.  4  were  judged  to  be  questionably  Permian 
by  Dr.  Girty. 

East  and  southeast  of  Good  Spring,  along  the  road  between  Good 
Spring  and  Manvel,  the  road  runs  along  the  contact  of  the  Mesozoic 
and  the  Carboniferous.  The  red  shales,  sandstones,  and  conglomer- 
ates which  lie  between  the  Upper  Carboniferous  and  the  Jurassic  at 
Good  Spring  and  Olcott  Peak  are  wanting  about  4  or  5  miles  south- 
east of  Good  Spring,  and  the  calcareous  sandstones  of  the  Jurassic 
lie  directly  upon  the  Carboniferous. 

About  6  miles  south  of  Good  Spring  the  Lower  Carboniferous  seems 
to  be  overthrust  upon  the  Jurassic. 

IGNEOUS   ROCKS. 

At  Good  Spring,  near  the  southern  end  of  the  range,  Mr.  Gilbert '^ 
noted  a  flow  of  basalt.  Other  than  this  no  igneous  rock  is  known  in 
the  whole  range.     Mr.  Rowe's  notes  record  the  following: 

At  the  Keystone  mine,  at  the  southern  end  of  the  range,  there  is  an 
acid  porphyry  dike  running  N.  17°  E.  Along  both  sides  of  this,  in  a 
talcose  material,  gold  is  found.     The  dike  dips  from  35°  to  40°  W. 


aU.  S.  Geog.  Siirv.  W.  One  Hundredth  Mer.,  Vol.  III. 


SPURR.] 


SPRING    MOUNTAIN    RANGE.  l75 


East  of  Bird  Spring  Range,  in  the  direction  of  the  Colorado  River, 
there  appear  to  be  extensive  lava  fields. 

STRUCTURE. 

The  general  observed  strikes  and  dips  of  the  strata  in  the  Spring 
Mountain  Range  have  been  plotted  by  the  writer  from  different  points. 
The  results  show  more  complex  folding  than  in  any  of  the  mountain 
ranges  to  the  north  and  east,  and  to  this  folding  the  irregular  shape 
of  the  range  is  probably  due.  In  an  east- west  section  the  general 
structui-e  of  the  range  seems  to  be  a  broad  syncline,  with  a  number  of 
minor  folds,  of  little  importance,  and  all  part  of  the  great  fold.  The 
axis  of  this  syncline  runs  northeast  and  southwest,  transverse  to  the 
general  trend  of  the  mountains  and  parallel  to  the  axes  of  the  folds 
in  Las  A^egas  Range,  already  described,  and  well  over  to  the  western 
side  of  the  mountains.  Mr.  Gilbert"  gives  a  section  of  the  Carbon- 
iferous rocks  at  Cottonwood  Spring,  Avhich  shows  the  southeasterly 
side  of  this  general  syncline. 

At  a  point  on  the  eastern  face  of  the  range,  due  southwest  from 
Corn  Creek  in' Las  Vegas  Valle}^  a  sharp,  slight  anticline,  constitut- 
ing a  wrinkle  in  the  general  syncline  and  with  a  parallel  axis,  may  be 
observed.  On  the  other  side  of  the  range  a  similar  anticline  runs 
along  the  foothills  northward  from  White's  ranch  for  some  distance. 
It  afterwards  appears  to  pass  into  and  occupj^the  narrow  north-south 
valley  l^etween  the  northern  end  of  the  Spring  Mountain  Range  and 
the  low  clusters  of  mountains  immediately  west. 

In  a  north-south  section,  however,  the  structure  of  the  Spring  Val- 
ley Range  appears  to  be  anticlinal,  the  strike  at  both  the  north  and 
south  end  being  in  general  east  and  west,  and  the  dip  varying  up  to 
65°  N.  at  the  north  end  and  up  to  about  20°  S.  at  the  south  end. 

Taken  altogether,  therefore,  the  range  exhibits  a  peculiar  fold,  anti- 
clinal in  a  north-south  section,  and  showing  a  slightly  complicated  or 
wrinkled  synclinorium  in  an  east-west  section.  The  portions  of  the 
center  of  the  syncline  that  should  lie  flat  dip  north  and  south  at  each 
limb  of  the  anticline. 

Except  at  the  northern  end  the  rocks  of  the  range  are  chiefly  Car- 
boniferous. At  the  northern  end  the  Cambrian  rocks  are  brought  up, 
probably,  by  at  least  two  heavy  east-west  faults.  The  northernmost 
of  these  faults  observed  lies  north  of  Hornet  Spring,  and  has  appar- 
ently brought  the  Cambrian  quartzite  into  juxtaposition  with  the 
Cambrian  limestone,  which  stratigraphicall}^  overlies  it.  The  throw 
of  the  fault  must  be  at  least  1,000  feet,  and  its  course  can  be  traced 
across  the  country  by  the  break  in  the  quartzite.  The  second  fault 
lies  3  or  4  miles  south  of  here,  just  south  of  Hornet  Spring.  It  is 
probably  parallel  to  the  first,  although  it  can  not  be  traced  so  easily, 


L 


a\J.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  III. 


176 


GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 


«      CS 


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since  it  separates  one  limestone 
body  from  another.  Bnt  the  lime- 
stone to  the  north  is  probably  Mid- 
dle Cambrian,  while  to  the  south  it 
is  Upper  Carboniferous.  A  ver- 
tical displacement  of  several  thou- 
sand feet  is  here  evidenced,  the 
downthrow  being  to  the  south,  as  ■ 
is  also  the  case  with  the  first  fault  '■ 
mentioned. 

These  two  heavy  faults  have 
the  same  general  direction  as  the 
heavy  fault  described  in  Las  Ve- 
gas Range,  and  like  it  they  have 
no  primary  effect  on  the  topogra- 
phy, being  marked  by  no  scarps- 
(fig.  22). 

A  third  fault  is  suspected  at  the 
northern  end  of  the  range,  sepa- 
rating the  Carboniferous  limestone 
from  the  supposedly  Silurian  lime- 
stone of  the  immediately  adjacent! 
Desert  Range.  If  this  fault  ex- 
ists, its  downthrow  is,  like  the 
others,  to  the  south  (fig.  22). 

The  following  important  ol^ser- 
vations  on  structure  have  been; 
taken  directly  from  Mr.  Rowe's; 
notebooks,  after  the  writing  of  the; 
above : 

About  10  miles  west  and  north- 
west of  Mule  Spring,  the  Upper i 
Carboniferous  is  thrown  into  a  se- 
ries of  minor  faults  running  in  a 
nearly  northwest  direction, 
l^itch  is  very  heavy  toward 
south.  These  are  probably 
southern  ends  of  the  folds 
uplifts  which  have  brought  up 
Charleston  Peak.  Together  with 
the  folding  there  was  a  great  deal 
of  minor  faulting.  A  fault  with 
a  throw  of  a  few  hundred  feet  is 
seen  about  one-half  mile  west  of 
Mule  Spring.  On  the  east  side  of 
Mule  Spring  is  a  steep  escarpment 


The 
the 
the 

and 


5PURK.]  SPRING    MOUNTAIN    RANGE.  177 

3omj)Osed  of  Uppei"  Carbouiferous  limestoues  overlying  red  shales. 
[u  this  escarpiiieiit  is  shown  a  minor  fault  or  a  slight  broken  fold 
R^hich  appears  to  be  I'ecent  and  has  directly  displaced  the  surface. 

On  the  west  side  of  Mule  Spring,  at  Mule  Spring  Mountain,  the  same 
formations  are  shown  in  a  similar  escarpment.  Here  the  beds  are 
bhrown  into  minor  folds  and  faults. 

A  great  fault  runs  in  a  northerly  to  northwesterly  direction  directly 
bhrough  the  center  of  the  main  Spring  Mountain  Range  and  through 
the  minor  ranges  which  are  coutinous  with  it  on  the  south  (see  map, 
PL  I).  This  is  shown  10  miles  north  of  Wilson's  ranch,  where  it 
funs  nearly  due  north.  It  was  also  observed  east  of  Mountain  Spring 
(fig.  34),  and  at  the  east  base  of  Olcott  Peak  (fig.  23),  and  was  traced 
past  Good  Spring  to  the  southeast.  At  Good  Spring  its  course  is  north 
and  south. 

Olcott    Peai 


Fig.  23.— Section  showing  the  great  fault  at  Olcott  Peak;  after  R.  B.  Rowe. 
1.  Lower  Carboniferous  limestones.  5.  Mesozoic  red  beds. 

3.  Upper  Carboniferous  limestones.  6.  Mesozoic  heavy  white  sandstone. 

I  Mountain  Spring  occupies  the  center  of  the  important  anticline 
which  forms  Olcott  Peak  or  Potosi  Mountain.  East  of  Mountain 
Spring  there  is  exposed  the  great  fault.  East  of  the  fault  is  an  ero- 
sion scarp  (fig.  24). 

Between  Wilson's  ranch  and  Red  Spring,  and  about  10  miles  north 
of  Wilson's  ranch,  there  is  an  overthrust  fault,  by  which  the  Carbonif- 
erous limestone  is  thrust  over  the  massive  red  Mesozoic  sandstone. 
Three  important  faults  are  shown  here — two  running  parallel  and 
nearly  north  or  west,  the  other  (the  great  fault)  running  at  right 
angles,  or  nearly  north  and  south. 

A,t  Cottonwood  Spring  the  apparent  section  is : 

Jurassic. 

Upper  Carboniferous. 

Red  Beds. 

Jurassic. 

Upper  Carboniferous. 

This  can  only  be  explained  by  a  fault.  It  is  to  be  inferred  that  the 
fault  is  an  overthrust.     No  direct  evidence  was  seen. 

Bull.  208—03 12 


178  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH   PAEALLEL.     [bull.208. 


About  1  mile  south  of  Cottonwood 
Spring  the  Carboniferous  rocks 
strike  S.  63°  W.,  and  dip  30°  NW. 
About  6  miles  east  of  Cotton- 
wood Spring  a  great  escarpment 
consists  of  Upper  Carboniferous 
beds  underlain  by  reddish  shales 
and  sandstones.  Mr.  Rowe's  sec- 
tion indicates  that  the  escarpment 
has  been  formed  by  the  erosion  of 
these  softer  beds. 

In  the  valley  east  of  the  Cotton- 
wood Spring  escarpment  there  is 
probably  a  fault  within  the  shale 
belt.  This  must  be  an  overthrust 
fault  along  bedding  planes,  because 
everything  r.ppears  to  be  conform- 
able. Red  beds  of  the  Carbonifer- 
ous overthrust  on  the  red  beds  of 
the  Mesozoic  make  the  fault  diffi- 
cult to  see.  Two  or  three  days' 
search  failed  to  reveal  any  direct 
indication  (fig.  24). 

There  is  some  minor  faulting 
'shown  in  the  Upper  Carboniferous 
strata  about  Cottonwood  Spring, 
and  some  minor  folding  in  the  Ju- 
rassic east  of  the  springs. 

On  the  divide  between  Good 
SiDring  and  Cottonwood  Spring 
there  appears  to  be  some  very 
sharp  folding  or  faulting  at  right 
angles  to  the  general  trend  of  the 
great  faults,  and  at  right  angles  to 
the  great  fault  running  on  the  east 
side  of  the  Charleston  Range. 

The  great  fault  lying  on  the  east 
side  of  the  Spring  Mountain  Range 
may  be  followed  easily  northward 
from  Good  Spring  to  the  divide  be- 
tween Good  Spring  and  Cottonwood 
Spring,  12  miles.  On  the  east  side 
of  the  fault  is  heavy-bedded  red 
sandstone  and  red  shales.  On  the 
west  is  Middle  or  Lower  Carbon- 
iferous  and   Upper   Carboniferous 


pj  ^ 


►^  ft 


^Cl 


mm 

m 


vMountain  spring 


W- 


g     CD      tD 


Wilson  rancli 


fc   £?  ^ 


,  CottorrwoocL  spring 


f/'roi?3b/y  o^-ertfirust  f3u/t 
or?  bedd/rrg  p/3f7ej 


Las  Vegas  "Valley 


SPURR.] 


SPRING    MOUNTAIN    EANGE. 


179 


wedged  in  the  fault  by  tlie  drag- 
(fig.  23).  The  section  given  bj^  Mi\ 
Rowe  shows  an  anticline  over- 
thrown to  the  east  and  faulted. 
The  fold  is  cut  deeply  by  canyons. 
Along  its  axis  the  rocks  are  much 
crushed  and  broken,  and  much 
minor  faulting  is  visible  in  places. 
This  great  fault  line  was  followed 
north  toward  AYilson's  ranch.  It 
changes  its  course  from  about  15° 
west  of  north,  south  of  the  summit, 
to  45°  west  of  north,  north  of  the 
summit. 

About  o  miles  north  of  Good 
Spring  the  Carboniferous  is  folded 
into  a  sharp  anticline  and  sj'ncline. 

The  general  structure  of  the  Bird 
Spring  Mountains  seems  to  be  anti- 
clinal, with  a  channel  of  erosion 
along  the  apex  of  the  anticline. 
There  is  a  fault  along  the  east  side 
of  the  range  which  brings  the  Lower 
Carboniferous  against  the  red  shales 
and  sandstones  of  the  Mesozoic. 
This  fault  runs  uortliAvest  and 
southeast  (see  fig.  25).  About  14- 
miles  north  of  Bird  Sxjrings  there  is 
another  fault,  which  crosses  the  first 
one  at  an  angle  and  brings  the 
Lower  and  Upper  Carboniferous 
together. 

About  6  miles  south  of  Good 
Spring  the  Lower  Carboniferous  is 
overthrust  upon  the  Jurassic.  The 
rocks  are  very  much  disturbed  along 
the  fault  line. 

About  three-quarters  of  a  mile 
south  of  the  summit,  between  Good 
Spring  and  Wilson's  ranch,  there 
is  a  fault  which  brings  the  Upper 
Carboniferous  above  the  Jurassic. 
The  fault  has  a  nearly  due  north- 
west course.  About  3  miles  south- 
east of  the  summit  there  is  another 
fault,  also  running  due  west,  which 


B  ^ 


1\  m 


e  g 


^ 


180  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

brings  the  Upper  Carboniferous  and  Jurassic  against  the  Lower  Car- 
boniferous. These  faults  are  nearly  normal  to  the  direction  of  the 
main  northwest-running  faults.  Minor  folds  shown  at  the  summit 
seem  to  be  at  right  angles,  or  nearly  so,  to  tlie  main  folds  running 
northwest. 

About  (3  or  7  miles  west  of  Corn  Creek,  on  the  south  side  of  the 
valley  between  Las  Vegas  Range  and  Spring  Mountain  Range,  tliere 
is  apparently  a  fault  bringing  the  Cambrian  against  what  is  probably 
the  Carboniferous.''  The  Cambrian  comprises  a  number  of  parallel 
ridges  running  east  and  west.  The  strata  dip  north.  Each  of  the 
ridges  has  a  steep  escarpment  facing  south.  Possibly  there  is  a  series 
of  faults  running  parallel  to  the  strike. 

Just  south  of  Indian  Spring,  at  the  northern  end  of  the  range,  the 
Upper  Carboniferous  limestones  show  considerable  minor  faulting 
and  folding.  Except  where  locally  folded,  the  dip  of  these  rocks  is 
generally  southwest.  About  one-half  mile  south  of  the  spring,  yel- 
lowish arenaceous  limestone  is  brought  by  a  fault  against  dark-blue 
cherty  limestone.  The  rocks  are  much  broken,  also,  bj^  minor  faults, 
which  are  hard  to  observe.  An  unconformity  is  shown  in  several 
places  between  the  red  shaly  Carboniferous  beds  and  the  overljang 
Carboniferous  limestone. 

ORE    DEPOSITS. 

In  the  extreme  southern  part  of  the  range  is  the  old  Potosi  or  Yel- 
low Pine  mining  district.  Here  there  are  veins  of  argentiferous  galena 
in  the  limestone.^ 

AREA   SOUTH   OF   SPRING   MOUNTAIN. 

From  Mr.  Rowe's  notebooks  the  following  information  is  taken : 
The  range  on.  the  east  side  of  State  Line  Pass,  about  12  miles  soutli 
of  Good  Spring,  shows  fossiliferous  Carboniferous  limestone  on  the 
west  side.  The  limestone  on  the  east  side  is  probably  also  Carbonif- 
erous, but  no  fossils  were  found.  Tlie  section  made  by  Mr.  Rowe 
seems  to  show  faulting  separating  the  two  limestones.  The  beds  dip 
throughout  the  whole  section  to  the  west. 

Mr.  H.  ^y.  Turner  has  kindly  supplied  the  following  note: 
Locality  on  the  boundary  line  between  San  Bernardino  County, 
Nev.,  and  Lincoln  County,  ISTev.,  at  State  Line  Pass,  at  about  G,000 
feet  elevation.  Mr.  Schuchert  states  that  the  collection  wliicli  was 
made  by  F.  C.  Boj^ce  contains  two  sj)ecies — a  CJucdetes,  which  is 
usually  identified  as  C.  milleporaceus  Edwards  and  Ilaime,  and  a 
Productus  of  the  P.  cora  type.  The  horizon  from  wliicli  these  fossils 
are  derived  is  Carboniferous,  and  probably  Upper  Carboniferous. 

«This  is  very  likely  the  same  fault  as  described  above  by  the  writer  (J.  E.  S.). 
&Geol.  Surv.  California,  Vol.  I,  p.  471. 


SPURR.J  KAWICH    RANGE    AND    RALSTON    DESERT.  181 

The  north  end  of  the  jNIeCnlloli  Mountains  is  Carboniferous  and 
seemed  to  be  lithologieally  like  the  Carboniferous  of  the  Bird  Spring- 
Mountains,  consisting  large!}'  of  light-gray  arenaceous  limestones. 

KAWICH    RANGE. 

The  Kawich  Range  forms  the  southern  continuation  of  the  Hot 
Creek  Range,  from  which  it  is  separated  at  its  northern  end  onh'  by 
a  narrow  transverse  pass.  From  this  point  it  extends  due  south  about 
60  miles,  where  its  southern  end  runs  out  into  the  desert  valley. 

TOPOGRAPHY. 

The  range  is  high  and  is  deeply  eroded  into  bold,  craggy  mountains. 
On  both  sides  the  slope  of  the  mountains  is  steep,  es]3ecially  on  the 
west,  where  there  are  almost  impassable  cliffs.  On  the  flanks  of  the 
range  on  both  sides  of  the  rugged  backbone  are  smoother,  mesa-like 
forms. 

SEDIMENTARY   ROCKS. 
TERTIARY. 

The  only  stratified  rocks  known  in  the  Kawich  Range  are  the  rhj'o- 
litic  tuffs  and  sandstones  which  occur  in  the  pass  between  the  Kawich 
and  the  Hot  Creek  mountains  and  which  also  mantle  around  the  north- 
ern base  of  the  Kawich  Range.  These  strata  are  evidently  the  same 
as  those  described  at  Twin  Springs,  between  the  Pancake  and  the 
Reveille  ranges.     They  are  closely  associated  with  Tertiarj^  rhyolites. 

IGNEOUS   ROCKS. 

The  igneous  rocks  constitute  the  whole  of  the  main  range,  so  far  as 
noted.  The  rough,  deepl}'  eroded  central  mass  of  the  mountains  is 
composed  of  biotite-rhyolite  similar  to  the  basal  rhyolite  of  the  Reveille 
Range.  In  these  rhyolites,  as  in  those  of  the  Reveille  Range,  there  is 
a  pronounced  north-south  jointing  or  sheeting  which  is  not  found  in 
the  younger  lavas.  The  dissected  mesas  found  in  a  narrow  belt  at  the 
base  of  the  mountains  are  composed  chiefly  of  more  basic  lavas,  with 
some  acid  lavas.  From  the  western  side  of  the  range,  near  its  north- 
ern end,  specimens  of  tordrillite  and  biotite-andesite  were  collected. 
In  tlie  pass  between  the  Kawich  and  the  Hot  Creek  niountains  decom- 
posed andesite  was  found. 

At  the  northern  end  of  the  Kawich  Range  the  rhj^olite  abuts  against 
the  Paleozoic  strata  of  the  Hot  Creek  Range  in  such  a  way  as  to  show 
that  the  mountains  of  the  Hot  Creek  Range  were  already  eroded  out 
of  the  limestones  before  the  rhyolites  were  extruded. 

RALSTON   DESERT. 

East  of  the  Sierra  Nevada  there  is  a  belt  of  mountain  ranges  which 
have  a  Paleozoic  or  old  granitic  core,  which  have  considerable  heights, 
and  whose  general  trend  is  northwest  and  southeast,  parallel  with  the 
face  of  the  Sierras.  In  this  belt  the  rocks  show  frequently  compressed 
or  even  overthrown  folds,  yet  have  experienced  vastly  less  compres- 


182  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

sion  than  the  intensely  folded  and  sheared  strata  of  the  Sierra.  East 
of  these  auxiliary  ranges  there  is  a  belt  which  is  comparatively  free 
from  Paleozoic  or  old  granitic  ranges.  It  has  been  covered  in  many 
places  by  late  Tertiary  or  Pleistocene  lavas,  so  as  partly  to  conceal 
the  fact  that  it  is  a  broad  depression,  but  nevertheless  this  character 
is  still  traceable  and  even  well  marked  on  a  topographic  map.  This 
great  belt  runs  northwest  and  southeast,  parallel  with  the  Sierra,  and 
separates  the  region  of  northwest-trending  ranges  on  the  west  from 
the  north-south  trending  ranges  on  the  east. 

The  Ralston  Desert  forms  a  portion  of  this.  Northwest  of  the  Ral- 
ston Desert  the  depression  is  continued  by  the  lower  end  of  Big  Smoky 
Valley,  by  Sinkavata  and  Gabbs  valleys,  and  farther  north  by  the 
region  of  Carson  and  Pyramid  lakes.  Beyond  this  it  appears  to  run 
up  into  Oregon. 

On  the  south  the  Ralston  Desert  is  separated  from  the  Amargosa 
Desert  bj^  an  irregular  belt  of  late  Tertiary  volcanic  mesas,  through 
which  Fortymile  Canyon  is  cut.  At  the  south  end  of  the  Amargosa 
Desert  the  open  belt  becomes  narrow,  but  farther  south  passes  into 
the  Mohave  Desert. 

The  Ralston  Desert  is  bounded  on  the  north  and  south  by  late 
Tertiary  volcanic  mesas,  which,  indeed,  are  found  throughout  its  ex- 
tent, so  that  these  boundaries  are  rather  arbitrarily  taken.  On  the 
west  the  desert  ends  at  the  chiefly  Paleozoic  Silver  Peak  and  Grape- 
vine ranges,  while  to  the  east  it  is  limited  chiefly  by  the  rugged 
Kawicli  Range,  which  apiDcars  to  be  j)rincipall3^  rhyolite. 

In  general  the  desert  consists  of  an  irregular  but  nearly  level  sandy 
plain,  broken  by  bunches  of  low  mesas  or  slightly  eroded  volcanic 
mountains.  Stonewall  Mountain,  which  lies  about  30  miles  east  from 
Lida,  is  an  exception  to  this  topograph}^,  being  a  high,  rugged  grouj), 
reaching  probably  9,000  feet  in  altitude,  or  4,000  feet  above  the  desert 
at  its  base.  The  northern  side  of  this  mountain  is  a  steep  cliff:  escarp- 
ment, probably  1,000  or  1,200  feet  high,  and  is  perhaps  a  simple  fault- 
scarp.     (See  PI.  VII,  A.) 

'  IGNEOUS    ROCKS. 

RHYOLITES. 

Stonewall  Mountain  is  entirely  made  up  of  rhyolite,  and  has  been 
so  deeply  eroded  that  it  can  not  be  of  very  recent  age.  This  rock  is 
probably  the  same  as  the  rugged  rhyolite  core  of  the  Kawich  Range. 
Northeast  of  Stonewall  the  low  mountains  in  which  Cactus  Corral  is 
situated  are  composed  of  rhyolite  and  tordrillite,  also  considerably 
eroded  and  probably  belonging  to  the  same  period. 

Most  of  the  hills  in  the  desert,  however,  show  comparatively^  slight 
erosion.  They  represent  thin  flows,  which  have  been  very  fluid  and 
so  have  run  comparatively  long  distances  from  the  vent,  at  a  very 
slight  angle  of  descent.  So  the  edges  ai-e  thin-benched  mesas,  while 
the  thicker,  inner  i^arts  are  irregular  hills.     While  these  mesas  are 


U.    S.    GEOLOGICAL  SURVEY 


BULLETIN   NO.    208       PL.    VU 


A.      NORTH   SCARP   OF   STONEWALL   MOUNTAIN.    RALSTON    DESERT. 
A  fault  scarp  (?). 


B.     PYRAMID    PEAK,   GRAPEVINE   RANGE,    FROM   THE   HEAD   OF   FURNACE   CREEK. 


SPURR.]  RALSTOjST    desert    AND    LONE    MOUNTAIN.  183 

evidently  younger  than  the  deeply  eroded  rugged  rhyolite  of  Stone- 
wall JMonntain,  j'et  they  seem  to  be,  in  part  at  least,  older  than  cer- 
tain horizontally  stratified  rhyolitic  claj^s  which  will  presently  be 
described  as  occupying  a  large  portion  of  the  desert  between  the  vol- 
canic hills  and  underlying  the  Pleistocene  sands.  Within  these  strati- 
fied clays,  aud  sometimes  capping  them,  are  also  beds  of  rhyolite,  very 
tine  grained  and  often  giassj'.  This  is  evidently  the  youngest  of  all 
the  rhyolites,  and  we  may  infer  that  the  rhyolitic  eruj)tions  lasted  a 
long  time,  beginning  with  those  of  Stonewall  Mountain  and  ending 
with  the  slaggv  flows  last  mentioned. 


The  latest  lava  of  the  desert  is  a  flow  of  slaggy  olivine-basalt,  hang 
at  the  base  of  Jackson  Mountain,  which  is  just  east  of  Lida.  This  is 
not  only  vounger  than  the  youngest  rhyolite,  but  is  apparently  younger 
than  the  erosion  of  this  and  the  underlying  sediments  to  form  the 
buttes,  of  which  Jackson  Mountain  is  one. 

SEDIMENTARY    ROCKS. 
TERTIARY. 

The  main  portion  of  Jackson  Mountain  consists  of  several  hundred 
feet  of  hardened,  horizontal  sands  and  clays,  containing  irregular 
fragmentri  of  rhyolite.  The  base  of  the  mountain  is  at  an  elevation 
of  5,100  feet,  so  that  the  uppermost  sediments  are  at  least  0,000  feet. 

In  the  valley  between  Stonewall  Springs  and  Cactus  Corral  there  is 
also  found  green,  hardened,  rhyolite  ash  containing  harder  fragments. 
It  is  evenly  and  horizontally  stratified  and  is  overlain  on  the  edges  by 
the  Pleistocene  gulch  dumps,  or  wash,  which  sometimes  extend  to 
the  middle  of  the  valle}^     The  ash  is  eroded  into  hummocks. 

This  thick  series  of  volcanic  sands  and  clays  was  probably  depos- 
ited in  a  body  of  standing  water  and  represents  a  lake  contemporary 
with  the  later  rhyolitic  eruption.  As  seen  from  the  sediment:;  of  Jack- 
son Mountain,  the  lake  must  have  been  at  least  1,000  feet  deep  or 
the  desert. 

PLEISTOCENE. 

Along  the  slopes  of  all  the  mountains,  especially  of  Stonewall  Moun- 
tain, are  great  wash  slopes  and  gulch  dumps  fringing  the  scarp.  This 
material,  flowing  down  into  the  valle}^  overlies  the  Tertiary  lake 
deposits.  In  the  bottoms  of  the  valleys  are  broad,  bare  mud  flats  or 
playas,  evidently  quite  recent  and  contein]3oraueous  with  the  gulch 
dumps.  They  seem  to  be  simply  sinks,  where  at  intervals  Avater  col- 
lects and  speedily  evaporates.  They  do  not  represent  the  residuum 
of  evaporated  Pleistocene  lakes  of  which,  moreover,  there  is  no  other 
evidence. 

LONE    MOUNTAIN. 

For  the  following  slight  description  of  Lone  Mountain  the  writer  is 
indebted  to  Mr.  Turner,  since  he  himself  saw  the  mountain  only 
from  a  distance.     The  mountain  really  forms  the  northern  end  of  the  ■ 


184  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

Montezuma  Ridge  of  the  Silver  Peak  Range,  but  on  account  of  its 
exceptional  height  and  prominence  has  been  given  a  separate  name. 

IGNEOUS    ROCKS. 

The  main  part  of  Lone  Mountain  consists  of  craggy,  light-colored, 
massive  granitic  rock. 

SEDIMENTARY   ROCKS. 

South  of  the  granitic  area  the  central  portion  consists  of  Cambrian 
limestone^  To  the  east  of  this  Cambrian  belt  is  a  belt  of  Silui-ian 
limestones,  as  determined  bj'  Mr.  Turner.  Along  tlie  west  flanks  of 
the  mountain  the  ujtturned  beds  of  the  Esmeralda  formation  (earlier 
Tertiary)  occur. 

SILVER   PEAK   RANGE. 

The  Silver  Peak  Range  is  short  and  somewhat  irregular' in  form. 
It  lies  immediately  east  of  the  northern  end  of  the  White  Mountain 
Range,  and  like  this  range  has  a  general  northwest-southeast  trend. 
On  the  north  the  range  is  separated  by  a  Ioav  pass  from  the  Monte 
Cristo  Mountains,  while  on  the  south  it  runs  into  the  northern  end  of 
the  Grapevine  and  Panamint  ranges.  From  near  the  southern  end 
of  the  range  a  spur  runs  off  to  the  north,  forming  the  eastern  boun- 
dary of  Clayton  Valley,  which  lies  between  it  and  the  main  range.  _ 

The  Silver  Peak  Range  was  studied  by  Mr.  H.  W.  Turner  during  || 
the  summer  of  1899,  and  the  mapping  of  the  formations  over  most  of 
the  range  has  been  kindly  furnished  b}*  Iiim  to  the  writer.  Most  of 
the  following  notes  on  the  geology,  designed  to  explain  the  map,  are 
also  due  to  him.  Mr.  F.  B.  Weeks,  of  the  Geological  Survey,  also 
spent  some  time  during  the  same  season  in  the  Silver  Peak  region, 
chiefly  for  the  purpose  of  collecting  fossils,  and  the  present  writer 
passed  through  it  on  his  wa}^  from  Columbus  to  Lida. 

The  range  is  mostly  made  uj)  of  folded  Paleozoic  rocks,  together 
with  intrusive  granite  and  a  large  auionnt  of  volcanic  material. 

SEDIMENTARY    ROCKS. 
CAMBRIAN. 

Fossils  obtained  by  Mr.  J.  K.  Clayton,  as  early  as  1866,  at  Silvei 
Peak,  and  fijst  regarded  as  Silurian  or  Devonian,  were  shown  by  Mr. 
Walcott"  to  be  Middle  Cambrian.  The  studies  of  Mr.  Turner  have 
furnished  many  details  concerning  these  Cambrian  rocks,  wliich 
occupy  considerable  portions  of  the  range.  In  some  of  the  Cam- 
brian limestones  masses  of  the  same  corals  occur  as  in  the  White 
Mountains  to  the  west,  so  that  Mr.  Walcott  regarded  the  two  occur- 
rences as  essentially  forming  part  of  a  single  reef.  ^ 

The  chief  area  of  Cambrian  is  north  of  Silver  Peak,  where  it  is 
capped  by  volcanic  rooks  in  many  places.     The  buttes  in  Clayton 


a  Bull.  U.  S.  Geol.  Siirvey  No.  30,  p.  38.  ^  Am.  Jour.  Sci.,  3cl  series,  Vol.  XLIX ,  p.  144. 


SPURR.]  SILVER   PEAK    RANGE.  185 

Valley  are  also  largely  Cambviau.     The  section  consists  of  comj)ara- 
1  ively  massive  limestones  and  cxnartzites. 

Along  the  road  leading  from  Silver  Peak  by  way  of  Barrel  Springs 
to  the  sontherii  end  of  the  range  at  Lida,  the  rocks  are  chiefly  Cam- 
brian limestones.  At  Lida  the  writer  collected  fossils  referred 
bv  ]Mr.  Yfalcott  to  the  Lower  Cambrian. 


Mr.  Turner  found  overlying  the  Cambrian  limestones  other  lime- 
stones containing  occasional  graptolites,  which  he  therefore  refers  to 
the  Sikirian.  An  area  of  these  Silurian  rocks  occurs  nortli  of  Benderes 
Pass,  while  a  belt  of  the  same  rocks  occurs  encircling  a  granitic  area 
north  of  Palmetto.  Silurian  rocks  are  also  found  on  the  southwest- 
ern edge  of  the  branch  mountain  ridge  above  described,  which  ma}^ 
be  called  the  "Montezuma  Ridge"  from  the  mining  camp  which  is 
situated  on  it. 

EARLY   TERTIARY. 

On  the  flanks  of  this  range  Mr.  Turner  has  described  sediments  to 
which  he  gives  the  name  of  the  Esmeralda  formation.^'  These  dej)osits 
consist  of  sandstones,  shales,  volcanic  tuffs,  breccias,  and  conglom- 
erates, and  great  thicknesses  of  lacustral  marls.  Coal  beds  and  plant 
remains  occur;  also  fossil  shells  and  fish  bones.  From  this  fossil  evi- 
dence the  age  of  the  beds  is  broadly  determined  as  late  Eocene  or 
early  Miocene.  The  beds  are  nearly  always  folded,  dipping  from  10° 
to  40°,  but  the  entire  thickness  may  be  several  thousand  feet. 

PLIOCENE. 

A  butte  in  Clayton  Valley,  northeast  from  Silver  Peak,  which  is 
capped  In'  olivine-basalt,  is  chieflj^  made  up  of  horizontalh"  stratified, 
partially'  consolidated,  green  volcanic  ash  and  tuff,  with  i^ebbles  of 
dark  hiva.  The  stratified  beds  are  undoubtedly  water- laid  and  are 
probably  unconformable  with  the  folded  Tertiary  series  just  described, 
which  occurs  in  patches  all  over  the  valley  to  the  north  of  here.  In 
general  appearance  the  beds  are  like  the  Pliocene  sediments  which 
have  such  a  broad  distribution  north  of  here,  such,  for  example,  as 
occur  on  the  pass  between  the  Candelaria  Mountains  and  the  Pilot 
Mountains.  They  are  also  similar  to  the  latter  occurrence  in  being 
capped  by  olivine-basalt  and  not  being  folded. 

Going  south  from  Silver  Peak  to  Barrel  Springs,  the  slopes  of  the 
mountains  consist  of  rolled  gravels  whose  pebbles  are  derived  from 
most  of  the  rocks  around,  including  the  lavas.  These  extend  back 
eastward  to  the  hills  of  the  Montezuma  Ridge,  which  are  made  up 
parti}'  of  volcanic  rock.  In  the  canyon  below  Barrel  Springs  the 
stratified  gravels  and  sands,  containing  rhyolite  pebbles,  are  found  to 
lie  against  the  eroded  edge  of  a  deposit  of  white  volcanic  ash  and 
pumice  apparently  water-laid,  and  this  ash  lies  against  the  eroded 

f  Am.  Geol.,  Vol.  XXV,  p.  168. 


186  GEOLOGY    OF    NEVADA  SOUTH    OP    40TH    PARALLEL,     [bull.208. 

edge  of  the  slightly  dipiDing  Cambrian  limestone.  These  gravels  and 
sands  seem  to  be  the  same  as  those  in  the  butte  described  above. 

In  the  outlying  hills  of  the  southern  part  of  the  range  just  east  of 
Lida  is  a  series  of  hardened,  stratified,  greenish  clays  and  sands  con- 
taining fragments  of  rhyolite.  These  clays  have  sometimes  been 
eroded  to  form  buttes,  especially  where  capped  by  lava.  They  are 
horizontally  stratified  and  undisturbed,  and  are  younger  than  the 
flow  of  olivine-basalt  which  sometimes  mantles  around  the  base  of 
the  buttes. 

The  deposits  in  these  different  localities  may  be  provisionall}^  cor- 
related with  the  other  sediments  which  have  already  been  ascribed  to 
the  Pliocene-Pleistocene  Shoshone  Lake. 

IGNEOUS   ROCKS. 

In  the  Silver  Peak  region  the  igneous  rocks  are  abundant  and 
varied. 

GRANITES. 

Granites  occupy  considerable  areas,  and  field  evidence  shows  that 
they  are  intrusive  into  the  Paleozoic  sediments,  but  not  into  the 
Tertiary  rocks. 

VOLCANIC   ROCKS. 

The  volcanic  history  of  the  region  is  of  considerable  complexity  and 
interest.  Mr.  Turner,  who  has  made  a  study  of  this,  has  kindly 
supplied  the  writer  with  the  information  that  the  succession  of  lavas 
in  this  district  has  been,  in  general,  (1)  rhj^olites,  (2)  andesites,  and  (3) 
basalts. 

ORE    DEPOSITS. 

At  Silver  Peak  there  are  rich  silver  and  gold  mines.  The  Cam- 
brian limestones  are  cut  by  pegmatitic  granitic  rock,  which  changes 
to  pegmatite  and  quartz  veins.  The  ores  appear  to  be,  partly  at 
least,  connected  with  these  intrusions. 

Numerous  other  localities  are  known  where  mineralization  has 
occurred.  At  Barrel  Springs  the  limestone  is  decomposed  and  stained 
along  a  vertical  zone  10  yards  wide  with  iron  and  copper.  The  honey- 
combed and  cavernous  appearance  of  the  rocks  shows  that  they  have 
been  the  channel  for  ascending  springs,  to  which  the  mineralization 
is  undoubtedly  due. 

At  Lida  the  writer  noticed  an  auriferous  quartz  vein  5  or  6  feet 
wide,  occurring  along  the  entire  contact  of  a  20-foot-wide  nearly 
vertical  dike  of  quartz-monzonite-porphyry  which  cuts  the  nearlj^ 
horizontal  Lower  Cambrian  limestones.  This  dike  is  evidently  a 
phase  of  the  general  granitic  intrusion  and  the  quartz  vein  is  an 
accompaniment. 


CHAPTER    IV. 

GREAT    BASIIvT    RAISTGES    OF    CAIjIFOR^^IA,    ?^0RTH    OF 
MOHAVE  DESERT. 

GRAPEVINE  AND   FUNERAL  RANGES. 

The  Grapevine  and  Funeral  ranges  are  practically  parts  of  a  single 
mountain  chain,  which  is  the  easternmost  of  the  Important  chains 
belonging  to  the  Sierra  Nevada  auxiliary  belt.  This  chain  faces  the 
Amargosa  and  the  Ralston  deserts  on  the  east,  and  has  a  northwest- 
southeast  trend.  The  Grapevine  Range  is  continued  on  the  north 
by  the  Silver  Peak  Range,  from  which  it  is  separated  only  by  a  com- 
paratively narrow  transverse  valley. 

That  portion  of  the  range  which  lies  immediately  north  of  Furnace 
Creek  has  been  sometimes  called  the  Amargosa  Range ;  but  in  the 
present  description  all  of  the  mountains  from  Furnace  Creek  north- 
ward will  be  included  under  the  single  term  Grapevine  Range, 
while  those  south  of  Furnace  Creek  will  be  described  as  the  Funeral 
Mountains.  To  this  southern  portion  of  the  range  the  name  Amargosa 
has  also  been  applied,  and  to  certain  parts  of  it  the  name  Black 
Mountains;  but  these  will  here  be  omitted. 

The  Funeral  Mountains  have  a  trend  somewhat  different  from  that 
of  the  Grapevine  Range,  being  more  nearly  north  and  south.  This 
change  is  accompanied  by  a  similar  change  in  the  trend  of  the  Pana- 
mint  Range,  which  lies  next  west. 

The  Grapevine  Range  is  not  of  great  width,  but  is  high  and  narrow, 
with  wild  scenery  (PI.  VII,  B).  The  Funeral  Mountains  are  lower,  and 
have  a  striking  air  of  desolation,  due  to  the  lack  of  vegetation  and 
the  dai-k,  gloomy  colors  of  the  rocks.  Both  the  Grapevine  and  Fune- 
ral ranges  are  cut  by  deep  canyons  which  sometimes  extend  quite 
through  the  range,  a  phenomenon  frequent  in  the  Great  Basin  ranges. 

At  Furnace  Creek  the  Grapevine  Range  fronts  the  Funeral  Range 
with  a  south-facing  scarp,  so  steep  as  to  be  almost  inaccessible  and 
about  4,000  or  5,000  feet  in  height.  At  the  base  of  this  scarp  the 
drainage  from  it  has  cut  a  channel  parallel  with  its^  front,  which 
forms  that  branch  of  Furnace  Creek  along  which  the  road  runs  across 
the  mountains. 

Both  the  Grapevine  and  the  Funeral  mountains  present  steep  sides 
to  Death  Valley,  which  are  bolder  than  the  western  side  of  the  valley, 

187 


188  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL.     [bull-SOS. 

SEDIMENTARY   ROCKS. 

Mr.  George  G.  Davis  has  kindly  sent  the  writer  samples  of  the  chief 
rocks  at  Gold  Mountain,  which  ajtpear  to  be  a  grayish,  rather  coarse- 
grained quart2ate  and  a  dark  bliie-gi*ay  slatj^  limestone  of  ancient 
appearance.     These  rocks  may  perhaps  be  Cambrian  or  Silurian. 

At  Boundary  Canj^on  Mr.  Gilbert  found  limestones  with  imperfect 
fossils,  which,  Avitli  the  stratigraphic  data,  serve  to  connect  the  rocks 
with  the  Cambrian  beds  observed  farther  east." 

At  the  extreme  southern  end  of  the  range,  at  Saratoga  Springs,  Mr. 
Gilbert*  has  noted  the  following  section  (from  toj)  to  bottom) : 

Section  at  Saratoga  Springs. 

Feet. 

1.  Gray  clay  slate 600 

2.  Yellow  slate,  with  beds  of  shaly  limestone 800 

3.  Bedded  and  slialy  limestone,  banded  in  purple,  yellow,  and  brown 350 

4.  Crystalline  limestone . 40 

5.  Dark-brown  qnartzose  and  argillaceous  conglomerate 140 

6.  Crystalline  limestone 85 

7.  Green  shale 20 

8.  Massive  hornblende  rock,  black  to  green 120 

.      Total 2,155 

According  to  Mr.  M.  R.  Campbell,''  the  rocks  composing  the  southern 
end  of  the  Funeral  Range  at  Saratoga  Springs  are  limestone,  shale, 
and  quartzite,  presumably  of  pre-Cambrian  age  and  containing  no 
fossils.  They  strike  north  and  south,  and  dip  about  50°  E.  No  Ter- 
tiary rocks  were  seen  in  the  southern  end  of  the  range  from  Saratoga 
Springs,  while  strata  resembling  those  exposed  at  Saratoga  Siorings 
could  be  traced  nortliAvard  for  several  miles  into  the  high  summits. 

SILURIAN. 

At  Furnace  Creek  Valley  the  writer  obsei'ved  bowlders  of  pure  white, 
vitreous  quartzite  extending  down  from  P^a^amid  Peak,  although  the 
main  mass  of  the  mountain  is  limestone.  This  quartzite  resembles 
the  Silurian  Eureka  quartzite,  so  persistent  in  Nevada,  and  the  rela- 
tion of  these  beds  to  those  overljing,  which  are  probabty  Devonian 
and  Carboniferous,  makes  it  probable  that  in  Pja^amid  Peak  and 
west  of  it  the  strata  are  largely  Silurian.  The  writer  has  been 
informed  by  Mr.  F.  B.  Weeks,  of  the  United  States  Geological  Survey, 
that  at  Grapevine  Peak  limestones  cariying  Lower  Silurian  fossils 
(probabl.y  corresponding  to  the  Pogonip  formation  of  Eureka)  occur, 
and  he  regards  these  Silurian  rocks  as  probablj^  continuous  southward 
to  Pyramid  Peak. 

DEVONIAN. 

In  the  mountains  east  of  Pyramid  PeaK:  a  great  series  of  easterly 
dipping   limestones  are  exjDosed,   in  Avhich   badly  preserved  fossils 

«U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  pp.  3S,  169, 181. 

6Ibid.,p.  170. 

c  Bull.  U.  S.  Geological  Survey  No.  aOO,  1903,  p.  14. 


SPURR.]  GKAPEVINE    AND    FUNERAL    RANGES.  189 

resembling  those  foiiiul  in  tlie  rocks  of  the  ranges  just  east  of  liere 
were  observed.  In  the  Kingston  Range  Devonian  fossils  were  col- 
lected from  similar  rocks,  and  from  the  great  thickness  of  the  section 
exposed  in  the  Grapevine  Range  at  this  point  it  is  likely  that  both 
the  Devonian  and  the  Carboniferous  may  be  represented  here. 

TERTIARY. 

In  the  eastern  part  of  the  range,  where  the  road  crosses  from  the 
Amargosa  Valley  into  Furnace  Creek,  there  is  found  a  great  amount 
of  conglomerate,  forming  high  hills.  These  conglomerates  are  very 
coarse  and  contain  rounded  pebbles  and  bowlders  of  all  sizes,  made 
up  of  reddish  and  white  quartzite  and  black  and  gray  limestones 
bearing  the  badly  preserved  Paleozoic  fossils  above  mentioned.  The 
conglomerate  is  as  hard  and  firm  as  the  rocks  from  which  it  is  derived. 
It  is  water-laid  and  well  stratified,  and  evidently  a  shore  formation. 
The  whole  thickness  exx^osed  is  estimated  at  4:,00()  feet.  It  is  sharply 
folded,  together  with  the  limestones  from  which  it  is  derived,  but  it 
abuts  abruptly  against  these  limestones  on  the  west. 

The  irregularity  of  the  contact  between  conglomerate  and  limesione 
denotes  a  great  erosion  interval,  yet  no  unconformity  of  attitude  is 
apparent. 

This  conglomerate  seems  to  fringe  tlie  north  edge  of  the  bold 
Paleozoic  scarp  of  the  Grapevine  Mountains  across  the  greater  por- 
tion of  the  range.  It  is  found  at  A^arious  points.  A  little  west  of 
Pj'ramid  Peak  conglomerate  occurs,  interbedded  with  and  running 
laterally  into  a  hard  limestone,  which  has  all  the  appearance  of 
being  calcareous  tufa.  A  specimen  examined  microscopically  bears 
out  this  idea  and  shows  that  the  rock  is  probabl}^  a  chemical  i)recipi- 
tate.  It  is  like  a  rock  found  in  crossing  the  Panamint  Range  from 
Death  Valley  to  Windy  Gaj:),  and  also  like  one  from  the  Esmeralda 
formation,  between  the  Candelaria  Mountains  and  the  Pilot  Range. 

Besides  these  rocks  there  occur,  as  parts  of  the  same  series,  semi- 
consolidated  gi-avels,  with  clays  j)artially  hardened  to  slaty  shales, 
limy  clays  partially  consolidated  to  argillaceous  secondary  limestones, 
and  sands  partially  hardened  to  cherty  and  limy  sandstones,  all 
interbedded.  All  these,  including  the  conglomerate  and  the  limestone 
tufa,  have  a  general  light-j^ellow,  often  greenish  color,  characteristic 
of  the  series. 

This  sedimentary  series  makes  up  the  greater  i:)ortion  of  the  Funeral 
Range.  Along  Furnace  Creek  Valley  and  on  both  sides  of  it  the 
mountains  consist  chiefly  of  y^ellow-green  strata  capped  by  basalt. 
The  lava  seems  to  occur  interbedded  with  the  sedimentaries,  as  well 
as  overlying  them.  The  series  is  here  consolidated  into  a  hard  clay 
rock,  with  occasional  thin  sandstone,  and  the  general  yellow-gi-een 
color  is  changed  in  places  to  reddish,  j^ellowish,  and  i^inkish.  The 
rocks  are   often  gyj)siferous  and  contain  abundant  grass  remains, 


190  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

which  are,  however,  indeterminable.  From  the  yellow-green  Tertiary 
series  in  the  hills  just  east  of  the  mouth  of  Furnace  Creek  there 
has  been  taken  much  borax,  which  occurs  as  borate  of  lime  in  beds  in 
the  strata.  Superintendent  Roach,  of  the  borax  works  at  Daggett, 
says  that  from  one  hill  here — Mount  Blanco — 200  tons  of  borax  a  day 
could  be  easily  shii)ped. 

On  the  eastern  side  of  -Death  Valley,  southward  from  Furnace 
Creek,  the  upturned  yellow-green  Tertiaries,  with  some  few  inter- 
calated sheets  of  lava,  constitute  the  mountains.  Beneath  some  of 
these  sheets  the  clays  are  baked  to  a  red,  natural  brick.  The  lavas 
seem  to  occur  chiefly  at  the  top  of  the  j^ellow-green  series,  or  at  a  still 
higher  horizon,  for  the  great  mass  of  beds  exposed  in  the  lower  por- 
tion of  Furnace  Creek  contains  no  lava  sheets;  yet  in  these  beds  occur 
occasionally  lava  bowlders  and  pebbles,  so  that  we  conclude  that  the 
period  was  one  of  continual  volcanic  activity.  From  fragments  of 
lava  picked  up  at  the  base  of  the  mountains  and  from  observations  at 
a  distance  tho  lower  lavas  seem  to  be  not  so  basic  as  the  upper  ones, 
which  are  chiefly  olivine-basalt.  A  single  specimen  of  biotite-andesite 
was  all  that  was  collected  to  represent  these  more  siliceous  volcanics. 

Near  the  summit  of  the  pass,  just  east  of  Furnace  Creek,  there 
come  in  above  the  yellow-green  Tertiary  se)-ies  softer,  dark-brown, 
honeycombed  conglomerates,  recalling  the  similar  rocks  of  Meadow 
Valley  Canyon.  Thin  sheets  of  basalt  are  interbedded  with  the  con- 
glomerates, but  the  great  sheets  lie  on  top.  Patches  of  this  same 
upper  conglomerate  series  were  elsewhere  observed,  and  at  one  place 
its  contact  with  the  underlying  yellow-green  series  appeared  slightly 
discordant.  The  conglomerate  contains  pebbles  and  bowlders  which  i 
are  chiefly  of  lava  and  must  have  been  derived  from  the  sheets  of 
basalt  which  were  periodically  poured  out  during  the  deposition  of  [ 
the  beds. 

A  rough  estimate  of  the  thickness  of  this  whole  series  of  slightly 
consolidated  beds  and  volcanics  puts  it  at  not  less  than  4,000  feet, , 
and  the  nature. of  the  sediments  shows  that  they  must  have  been  i 
deposited  in  standing  water.  The  presence  in  some  of  the  beds  of 
gypsum,  borax,  and  calcareous  tufa  shows  that  at  some  jDcriods  the 
waters  in  which  the  sediments  were  deposited  were  evaporated. 
They  were,  therefore,  those  of  an  inclosed  lake,  which  was  probably 
of  great  dimensions.  It  is  likely  that  a  large  portion  of  the  beds  wei-e 
deposited  in  fresh  water  at  a  period  different  from  that  in  which  the 
chemical  precipitates  were  laid  down. 

The  borax  in  these  beds  is  probabl}^  contemporaneous  with  the 
borax  deposits  in  similar  folded  Tertiaries  at  Daggett  and  elsewhere 
in  the  Mojave  Desert.  Between  these  two  localities,  moreover,  the 
strata,  so  far  as  known,  appear  to  be  roughly  continuous.  The  strata 
of  Mojave  Desert  are  exposed  on  a  grand  scale  at  Cajon  Pass,  where 
they  contain  beds  of  black  lignite. 


SPURR.]  GRAPEVINE    AND    FUNERAL    RANGES.  191 

Northward  from  Furnace  Creek,  at.  Silver  Peak,  are  found  beds  of 
the  Esmerakla  formation,  which  are  eutirel}^  similar  in  nearly  every 
respect  to  those  at  Furnace  Creek.  Moreover,  the  fossils  found  in 
the  Esmeralda  beds  indicate  a  nearly  similar  age  to  that  indicated 
by  fossils  found  in  the  Tertiary  strata  of  the  Mojave  Desert,  just  west 
of  Cajon  Pass. 

The  upper  part  of  the  Furnace  Creek  beds  is  identical  in  appear- 
ance with  certain  semi-indurated  and  slightly  folded  conglomerates 
and  sandstones  found  in  Meadow  Valley  Canyon,  which  have  been 
referred  to  the  Pliocene.'* 

PLEISTOCENE. 

At  the  lower  end  of  Furnace  Creek  the  steeplj^  dipping  Upper 
Tertiary  gravels  are  overlain  directly  and  unconformably  by  hori- 
zontal gravels,  which  are  partly  consolidated  and  form  bluffs  15  feet 
high. 

These  are  the  same  gravels  as  were  noted  on  the  eastern  flanks  of 
the  Panamint  Range,  on  the  road  crossing  to  Windy  Gap,  the  beds 
here  having  the  same  appearance  and  position.  Their  jjerfect  hori- 
zontality  indicates  that  they  are  perhaps  the  deposits  of  a  post- 
Tertiary  lake.  This  lake  was  a  few  hundred  feet  deep,  as  measured 
by  tlie  highest  of  these  sediments. 

It  therefore  api^ears  j)robable  that  the  Furnace  Creek  beds  repre- 
sent nearly  the  whole  of  the  Tertiary  period,  from  the  Eocene  through 
the  Pliocene.  It  is  jDossible  also  that  the  uppermost  lavas  belong  in  the 
Pleistocene,  for  they  are  fresh  olivine-basalt,  like  that  which  is  known 
to  have  been  extruded  throughout  the  Great  Basin  region  during  the 
Pleistocene.* 

A  considerable  portion  of  the  area  of  greatest  depression  is  occux)ied 
by  a  great  brown  desert.  This  has  the  api)earance  of  a  newly  jilowed 
field  in  color  and  form,  and  appears  soft.  On  examination  the  surface 
is  found  to  consist  entirely  of  hard  salt,  rendered  brown  by  a  mixture 
of  soil.  This  deposit  is  probably  the  result  of  the  evai)oration  of 
the  Pleistocene  lake. 

This  lake  was  fed  by  the  Amargosa  River.  The  writer  has  been 
informed  by  those  who  are  familiar  with  this  region  that  occasionally^ 
the  Amargosa  River  has  been  seen  to  be  200  feet  wide  at  the  southern 
end  of  Death  Valley,  although  generally  it  is  dry  on  the  surface  as 
far  uj)  as  Ash  Meadows.  Along  this  dry  course  it  flows  underground, 
as  is  shown  by  the  fact  that  water  may.  generally  be  found  by  digging 
a  few  feet  below  the  surface.  In  Death  Valley,  also,  water  can  be 
found  in  many  places  by  digging,  so  the  dregs  of  the  lake  may  be  said 
to  still  exist. 

"See  description  of  Meadow  Valley  Canyon,  Meadow  Valley  Range,  Mormon  Range,  and 
Virgin  Range. 

''See  J.  E.  Spurr,  Succession  and  relation  (jf  lavas  in  the  Great  Basin  region:  Jour.  Geol.,  Vol. 
VIII,  p.  636. 


192  GEOLOaY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL.     [bull.x'OS. 

IC4NEOUS   ROCKS. 
GRANULAR   ROCKS. 

Granitic  rocks  are  said  to  occur  at  Gold  Mountain,  at  the  northern 
end  of  the  range,  where  the  gold  ores  are  connected  with  theni.'^ 

OLIVINE-BASALT   AT    FURNACE   CREEK. 

The  Funeral  Mountains  are  capjjed  by  hea^'y  flows  of  pyroxene- 
olivine-basalt,  which  seems  to  have  been  slightly  involved  in  the  latter 
part  of  the  folding  wliich  affected  the  underlying  Tertiaries.  The 
rock  is  black  and  slaggy  and  is  identical  in  appearance  and  composi- 
tion with  the  Pleistocene  olivine-basalts  found  frequently  in  Nevada.* 

Besides  capping  the  Tertiar}^  sediments,  the  basalt  occurs  in  sheets 
which  are,  in  part  at  least,  certainly  contemporaneous  with  the  upper 
portion  of  the  sediments,  especially  the  conglomerate  series.  One 
basalt  sheet  was  noted  as  metaniori^hosing  the  underlying  conglomer- 
ates, but  not  the  upper  ones,  and  is  therefore  probably  a  flow  and 
not  an  intruded  sill.  Moreover,  the  i)ebbles  and  bowlders  in  the 
ui3j)er  conglomerate  series  are  largely  of  the  same  basalt. 

ANDESITE    AT    FUkxj^cE    CREEK. 

Beneath  the  basalt  sheets  there  is  a  certain  amount  of  less  basic 
volcanic  material  in  the  beds.  This  was  not  carefully  investigated, 
but  a  single  specimen  showed  that  biotite-andesite  is  represented. 

VOLCANICS  NORTH  OF  FURNACE  CREEK. 

North  of  Furnace  Creek  the  Avholc  northeastern  side  of  the  Grape-^ 
vine  Range  is  overlapped  by  the  sea  of  lava  v\diich  occurs  over  mostoi 
the  Ralston  and  Amargosa  deserts,  except  where  obscured  by  Terti- 
arj^  or  Pleistocene  detrital  accumulations.  At  the  north  end  of  the 
range  these  volcanics  may  connect  with  the  volcanic  area  just  north 
of  Gold  Mountain,  which  there  extends  to  the  western  side  of  th( 
range  and  is  probably  connected  with  the  lavas  at  the  northern  end 
of  the  Panamint  Range. 

Mr.  Gilbert'"  notes  that  rhyolite  occurs  a  few  miles  north  of 
Boundary  Canyon,  flanking  the  range  both  on  its  eastern  and  its  west-i 
ern  side. 

STRUCTURE. 

Mr.  Gilbert  '^  has  drawn  a  section  of  the  Graj^evine  Range  at  Bound- 
ary Canyon.  This  section  shows  essentially  a  main  anticlinal  fold, 
slightly  overthroAvn  to  the  west,  Avith  an  auxiliar}^  broad  anticline 


"Wheeler  Survey  Explorations  in  Nevada  and  Arizona,  War  Department,  1871,  p.  47 

I'J.E.  Spnrr,  Jour.  Geol.,  Vol.  VIII,  p.  636. 

'•U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  33. 

rflbid.,  p.  33. 


SPURK.]  GRAPEVINE    AND    FUNERAL    RANGES.  193 

fonniiiii:  the  slopes  of  the  vauiie  towunl  Death  Valley,  aiid  a  syncline 
between  the  two.  These  folds  are  much  broken  np  l)y  faults,  which, 
as  Mr.  Gilbert  notes,  are  not  only  longitudinal,  but  transverse." 

In  crossing-  the  mountains  at  the  junction  of  the  Grajievine  and 
Funeral  ranges,  on  the  road  leading  to  Furnace  Creek,  a  good  struc- 
ture section  was  obtained.  The  south-facing  scarp  of  the  Grapevine 
Mountains  shows  a  central  chief  anticline,  with  a  very  great  thick- 
ness of  uniformly  easterly-dipping  beds  on  the  east  limb.  AVest  from 
this  central  anticline,  whose  axis  is  immediately  west  of  Pyramid 
Peak,  there  is  a  second  anticline,  also  with  steep  dips,  in  the  moun- 
tains immediately  above  Death  Valley,  and  between  the  two  anti- 
clines is  a  slight  syncline.  On  the  south  side  of  the  pass,  in  the  lower 
Funeral  Mountains,  it  seemed  to  the  writer  that  there  is  about  the 
same  structure,  although  the  dips  ajjpear  to  be  decidedly  less.  No 
faults  were  noted  in  this  section,  though  the}'  very  likel}^  exist. 

The  folds  at  Furnace  Creek  are  probably  continuous  with  those 
shown  in  Mr.  Gilbert's  section.  As  the  writer  looked  along  the  face 
of  the  Grapevine  Mountains,  noi'thward  from  Furnace  Creek,  he 
thought  to  be  able  to  trace  the  western  anticline  at  least  as  far  as 
Boundary  Canyon. 

The  Tertiary  beds  of  the  Funeral  Mountains  have  therefore  been 
folded  together  with  the  Paleozoics  of  the  Grapevine  Range.  Yet  the 
Paleozoic  limestones  appear  to  have  in  general  steeper  dips  than 
the  Tertiary  strata.  Nevertheless,  the  chief  folding  has  come  about 
since  the  deposition  of  the  Tertiary.  Not  only  the  lower  Tertiary 
beds,  but  also  the  upper  conglomerates  are  folded,  and  even  to  a  cer- 
tain extent  the  interbedded  and  overlying  olivine-basalt,  which  is  of 
fresh  appearance  and  may  be  in  part  as  young  as  Pleistocene.  Cer- 
tainly, therefore,  the  upheaval  of  the  Funeral  Mountains  and  the 
present  Grapevine  Range  has  been  very  recent  indeed. 

This  is  illustrated  in  the  Funeral  Range,  which,  as  viewed  by  the 
writer,  seemed  to  consist  near  its  northern  end  of  two  anticlinal  ridges 
with  a  synclinal  valley  between.  This  synclinal  vallej^  is  occupied  by 
Furnace  Creek,  which  follows  the  folding  in  all  its  bendings.  The 
northwesterly  course  of  the  lower  portion  of  Furnace  Creek  is  caused 
by  a  corresponding  bend  in  the  synclinal  trough.  This  deflection  of 
the  Furnace  Creek  syncline  appears  not  to  be  continuous  into  the 
Paleozoic  strata  just  north  of  here,  and.  it  is  very  likely  due  to  the 
differential  folding  of  the  Tertiary  strata  against  the  hard  Paleozoic 
buttress.  In  the  summit  of  the  pass  above  Furnace  Creek,  this  fold- 
ing against  the  Paleozoic  cliff  is  well  shown  b}"  a  sharp  local  anticline 
in  the  Tertiary  beds,  the  north  limb  of  which  dips  from  20  degrees  to 
45  degrees  toward  the  Paleozoic  wall,  which  does  not  take  part  in  the 

cMr.  F.  B.  Weeks,  of  the  U.  S.  Geological  Survey,  found  in  1900  that  at  Grapevine  Peak 
the  main  range  was  decidedly  synclinal  in  structure,  the  axis  of  the  fold  in  general  transverse 
to  the  trend  of  the  range. 

Bull.  208—03 13 


194  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

flexure.     This  fold,  however,  is  of  slight  width,  the  dip  reversing  and 
flattening  a  hundred  yards  south.     (See  PL  VIII,  A.) 

RESUME. 

The  succession  of  events  in  the  Grapevine  and  Funeral  ranges  and 
in  the  region  of  Death  Valley  is,  then,  about  as  follows: 

1.  Deposition  of  a  thick,  conformable.  Paleozoic  series. 

2.  Elevation  to  a  land  mass,  without  marked  folding. 

3.  The  formation  of  sharp,  lofty  mountains,  with  deep  valleys. 

4.  The  deposition  of  the  thick  Tertiary  series.  This  took  place,  in 
part  at  least,  in  a  great  lake  or  inland  sea.  In  this  lake  were  deposited 
near  the  shores  conglomerates  and  breccias  derived  from  the  Paleozoic 
rocks;  in  the  other  portions  were  formed  silts  mixed  occasionally  with 
gravels.  During  the  deposition  of  this  series,  especially  the  later 
portion,  there  was  volcanic  activity,  and  sheets  of  lava  were  poured 
into  the  lake,  thus  becoming  intercalated  with  the  sedimentary  beds. 

5.  The  lake,  probably  generally  fresh,  was  at  certain  times  reduced 
and  evaporated,  so  that  beds  containing  salt,  borax,  silica,  and  lime 
were  chemically  precipitated  and  mingled  with  the  detrital  silts. 

6.  The  volcanics  changed  to  olivine-basalt.  These  lavas  are  asso- 
ciated with  well-stratified  sediments,  such  as  might  have  been  formed 
in  a  lake,  but  accurate  data  bearing  on  this  point  are  lacking.  The 
sediments  may  possibly  be  the  result  of  stream  action.  They  consist 
of  brown  and  red  conglomerates,  which  overlie  the  yellow-green  lake 
beds,  and  are  separated  from  them  by  some  slight  movement  and  per- 
haps an  erosion  gap. 

7.  Final  flows  of  olivine-basalt. 

8.  Probably  beginning  before  the  deposition  of  the  Tertiary,  but 
not  becoming  very  important  until  during  and  after  the  close  of  this 
period,  came  a  disturbance,  leading  to  rapid  folding.  The  crvist  was 
bent,  and  j)erhaps  broken,  forming  hills  and  valleys.  Death  Valley 
was  created. 

9.  The  mountains  were  eroded,  producing  minor  irregular  forms. 
The  climate  being  slightly  moister  than  now,  a  shallow  lake  a  few 
hundred  feet  deep  was  formed  in  the  bottom  of  Death  Valle3^  This 
soon  became  charged  with  salt,  borax,  etc.,  derived  chiefly  from 
the  leaching  of  the  earlier  lake  beds,  now  become  mountains.  At 
this  period  the  late  Pleistocene  shore  gravels  were  formed. 

10.  The  climate  becoming  drier,  the  lake  evaporated,  leaving  a  salt 
desert.  Since  that  time  there  has  been  only  a  slight  incision  of  the 
lake  shore  conglomerate  by  the  drainage  from  the  mountains  to  the 
dry  valley. 

AMARGOSA  VALLEY. 

The  Amargosa  Valley  lies  between  the  Kingston  and  Funeral 
ranges.  The  following  notes  are  from  Mr.  R.  B.  Howe's  notebooks, 
except  where  credited  to  Mr.  Campbell. 


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spuRR.l  AMARGOSA    VALLEY    AND    KINGSTON    EANGE.  195 

METAMORPHIC    ROCKS. 

Metamorphic  rocks  are  exposed  about  a  mile  below  the  China  ranch. 

SEDIMENTARY   ROCKS 
TERTIARY. 

Overlying  the  metamorphic  rocks  at  the  point  mentioned  above  are 
Tertiary  deposits.  These  Tertiary  lakes  were  dry  part  of  the  time,  or 
receded  to  a  great  extent  and  then  swelled  out  again,  for  talus  and 
lake  deposits  alternate  with  each  other  in  the  lower  Amargosa.  At 
China  ranch  the  Amargosa  River  cuts  through  the  Tertiary  beds  to 
a  depth  of  200  or  300  feet. 

Mr.  M.  R,.  Campbell  ^''  has  indicated  on  a  maj)  two  areas  of  Tertiary 
lake  beds  near  Amargosa  Valley,  one  around  Resting  Springs  and  the 
other  south  of  Ash  Meadow. 

STRUCTURE. 

At  China  ranch  the  Tertiaries  have  been  uplifted  so  that  they  dip 
at  a  high  angle.  The  structure  seems  to  be  monoclinal.  There  is  also 
some  faulting  in  the  Tertiary  beds.  Above  China  ranch  the  late  talus 
deposits  overlying  the  Tertiary  are  tilted  uj)  to  a  high  angle,  together 
with  the  Tertiary  rocks. 

For  a  distance  of  3  miles,  near  China  ranch,  the  Amargosa  River 
has  recently  cut  down  about  20  feet  into  an  old  river  deposit  or  wash. 
For  a  distance  of  about  1  mile  it  is  beginning  to  cut  down  4  or  5  feet 
farther.  This  is  shown  by  waterfalls  in  the  talus.  This  local  down- 
cutting  seems  to  indicate  recent  movement. 

Mr.  M.  R.  Campbell*  states  that  the  Tertiary  beds  in  this  valley 
bear  evidence  of  considerable  crustal  movement  since  their  deposi- 
tion. The  eastern  margin  that  rests  against  the  foot  of  the  Kingston 
Range  is  800  feet  higher  than  the  uppermost  beds  of  the  same  series 
at  the  foot  of  Funeral  Mountain.  This  indicates  a  depression  toward 
the  west,  in  the  direction  of  Death  Valley.  It  seems  possible  that 
the  change  was  due  to  tlu^  sinking  of  Death  Valley  to  its  present 
position  below  sea  level. 

KINGSTON   RANGE. 

The  Kingston  Range  lies  between  Pahrump  Valley  and  the  valley 
of  Amargosa  River.  The  Califoi-nia-Nevada  line  passes  along  its 
eastern  base.  Tlie  range  luis  a  northwest-southeast  trend  and  is  50 
or  60  miles  in  length.  At  its  northern  end  it  is  separated  by  a  short 
valley,  called  Stuart  Valley,  from  the  mountains  which  lie  directly 
north  of  Pahrump  Valley,  and  which  form  an  irregular  group  afford- 
ing a  partial  connection  between  tlie  Spring  Mountain  Rajige  and  the 
Kingston  Range.  This  group  will  be  described  together  with  the 
Kingston  Range. 


a  Bulletin  U.  S.  Geol.  Survey  No.  m).  f'Ibid.,  pp.  14, 15, 


196  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

The  Kingston  Range  generally  has  steep  fronts,  especially  along 
the  main  eastern  side,  where  it  faces  Palirnmp  Valley. 

SEDIMENTARY   ROCKS 
CAMBRIAN. 

Mr.  R.  B.  Rowe,  in  1900-1901,  discovered  and  described  Cambrian 
in  the  Kingston  Range.  The  following  information  has  been  taken 
from  his  notebooks : 

The  greater  part  of  the  Kingston  Range  is  made  up  of  Cambrian 
strata.  On  the  road  from  the  j)ost-office  at  Sand}^  to  Kingston  Peak 
there  are  sandstones  and  limestones,  with  metamorphosed  gray  schists 
cut  by  dikes. 

Kingston  Mountain  consists  of  a  central  core  of  granite,  which  is 
topped  on  tlie  north  and  northeast  by  a  fine-grained  white  quartzite 
with  reddish  bands.  The  succession  at  Kingston  Peak,  near  Horse 
Spring,  from  the  bottom  up,  is  as  follows: 

Section  at  Kingston  Peak. 

1.  White,  gray,  or  red  qiiartzites. 

2.  Red,  gray,  and  blue  slates,  and  heavy  beds  i)f  quartzite. 

3.  Dark  blue,  much  altered  limestone. 

4.  Light  gray,  arenaceous  limestone,  much  altered,  with  crystallized  calcite 

in  its  crevices  and  interspaces. 

5.  White  and  brownish  quartzite,  with  conglomerate  at  the  bottom.     This 

sometimes  alternates  with  the  red,  gray,  and  bine  slates. 

In.  some  ijlaces  the  wliite  quartzite  at  the  base  seems  to  run  into  a 
gray  gneiss. 

On  the  road  between  Manse  and  Resting  Springs,  througli  the  pass 
going  to  Tecopa,  there  is  an  excellent  section  of  the  mountains  east  of 
Resting  Springs.  The  Cambrian  seems  to  be  repeated  at  this  point, 
probably  by  a  fault.  At  Resting  Si)rings  the  thickness  of  the  Cam- 
brian, j)artly  estimated  and  parti}'  actually  measured,  is  about  1,500 
feet,  and  can  not  be  more  than  2,000  feet.  About  4  or  5  miles  north 
of  Resting  Si^rings  the  Cambrian  is  capped  by  lava. 

On  the  spur  of  the  Kingston  Range  ending  at  Resting  Springs,  at  a 
locality  about  2  miles  north  of  the  springs,  the  following  section,  from 
the  bottom  up,  was  observed : 

Section  £  miles  north  of  Resting  Springs. 

Feet. 

Heavy  sandstone,  probably  all  conglomeratic.  Observed  pebbles  were  all 
well-rounded  quartzite 2, 000 

Generally  gray  shales,  with  bands  of  sandstone 1 ,  000 

Dark-blue  limestone  with  shales  and  siliceous  limestones,  containing  trilo- 
bites  and  other  Cambrian  fossils 100 

Quartzitic  sandstones  and  shales 700 

About  7  miles  east  of  Resting  Springs  the  rocks  in  the  range,  which 
is  jjart  of  the  Kingston  Range,  are  in  j)art  Lower  Cambrian,  and  are  a 


-PUllIt. 


KINGSTON    RANGE.  ]97 


repetition  of  those  exposed  at  Resting  Springs.  There  is  shown  in 
these  mountains  about  4,000  feet  of  Lower  Cambrian  or  earlier  rocks. 
Tliey  consist  chiefly  of  reddish  and  gray  sandstone,  some  calcareous 
sandstones,  and  red  and  blue  shales.  Fossils  were  found  within  about 
1,500  feet  of  the  top,  and  none  below  that.  Although  a  diligent  search 
was  made,  they  were  found  only  in  one  ledge,  and  seemed  to  be  poorly 
represented  even  there.  About  800  feet  below  the  top  of  the  shale 
and  sandstone  formation,  fossils  are  very  abundant  in  some  very 
thin  sandstones.  Thej^  consist  mainly  of  trilobites,  Hyolifhes,  and  a 
brachiopod. 

In  the  pass  east  of  Resting  Springs,  about  800  feet  beneath  the 
dark  blue  limestones,  Cambrian  fossils  were  collected.  The  section 
consists,  from. the  bottom  up,  as  follows: 

Section  in  2'xifiii  eaf<t  of  Reading  Springs. 

Feet. 

1.  Rpddisli  sandstones  and  shales,  bhie  shales,  calcareous  sandstones,  etc. 

About  2,500  feet  from  the  bottom  Cambrian  fossils  are  fonnd,  and  they 

,are  also  found  800  feet  from  the  top 4, 000 

2.  Massive  dark-bhie  limestone,  apparently  containing  no  fossils 2,000 

.3.  Light-gray  limestone  in  more  or  less  thin  layers 300 

4.  Shaly  brown  sandstone,  with  beds  of  limestone.     Contains  small  trilobites 

and  lingtiloid  shells.    Probably  Cambrian  and  possibly  Lower  Cambrian  _         20 

About  8  miles  east  of  Resting  Springs  is  found  No.  5  of  the  sec- 
tion, consisting  of  light-gra}^  and  dark-l)lue  limestone,  moi-e  or  less 
massive;  thickness,  about  2,000  feet.  There  is  an  apparent  uncon- 
formity between  this  limestone  and  tlie  underlying  formations. 
Certain  parts  of  the  limestone  are  penetrated  by  whal  may  be  worm 
l)orings,  now  filled  with  calcite. 

About  3y  miles  east  of  Twelvemile  Springs  is  l)lue  and  gray  lime- 
stone. From  loose  blocks  found  li-ilobites  were  collected,  which  did 
not  appear  to  Mr.  RoAve  to  be  Lower  Cambrian,  but  to  be  sonuMvhere 
l)etween  the  Trenton  and  the  Lower  Cambrian. 

On  the  road  fi-om  Resting  Springs  1o  Tecopa  the  rocks  ai-e  largely 
conq^osed  of  gneiss  containing  pegmal  ite  dikes.  Upon  the  gneiss  lie 
shales,  sandstones,  and  limestones  of  Ca-mbrian  or  pre-Cambi-ian  age. 

Oil  the  road  from  Palirump  ranch  to  Furnace  Creek,  along  the 
nortliern  edge  of  the  Kingston  Range,  j\Ir.  Rowe  collected  Lower 
Cambrian  fossils  from  1-he  gray  shaly  sandstone. 

IIEVONIAN. 

Tlu»  range  was  crossed  by  the  writer"  on  the  ri^ad  between  Pah- 
I'limp  Valley  and  Furnace  Creek,  in  the  Funeral  Range,  this  road 
li^ading  past  Sulphur  Spring  and  tlie  liead  of  Stuart  Valley. 

Near  Sulphur  Spring  tliere  outcrops  a  crystalline,  dark-blue,  often 
line-grained,  siliceous,  fetid  limestone.     It  is  much  altered  by  folding, 

".^.  E.  s. 


198  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL.     [bull.S 

but  a  small  lot  of  fossils  was  obtained,  which  are  regarded  by  Dr. 
Girt}'  as  Devonian.     The  species  ai^e  as  follows: 

Zaphrentis  sp.  Spirifer  maia. 

Orthis  sp.  Spirifer  maia  (small  variety)?. 

Chonetes  deflectusr.  Spirifer  argentarius. 

About  10  miles  northwest  of  the  fossil  locality  above  mentioned 
occurs  a  Tertiary  conglomerate,  containing  pebbles  of  this  limestone 
and  quartzite,  and  from  these  pebbles  another  collection  of  fossils 
was  made,  which  are  determined  by  Dr.  Girty  to  be  Devonian : 

Zaphrentis  sp.  Spirifer  indeterminable. 

Crinoid  stems.  Athyris?  sp. 

Bryozoan  fragments.  Atrypa  missourensis. 

Spirifer  pinyonensis.  Phaethonides  sp. 

MESOZOIC. 

At  the  summit  of  the  pass  between  Manse  and  Tecopa  Mr.  Rowe 
noted  that  the  Paleozoic  limestone  is  overlain  by  light-gray  and 
chocolate  sandstones,  reddish  and  red  sandstones,  and  dark-brown 
sandstones.  Some  of  these  are  conglomeratic.  Lithologically,  this 
formation  is  like  the  Mesozoic  of  the  Spring  Mountain  Range.  These 
rocks  seem  to  be  unconformable  with  the  underlying  dark-blue  Paleo- 
zoic limestone,  the  dip  of  the  Paleozoic  rocks  being  about  10  or  11 
degrees  greater.  The  supposedly  Mesozoic  rocks  are  about  1,000  fee) 
thick,  and  are  overlain  to  the  south  by  a  lava  bed. 

TERTIARY. 

On  the  border  of  the  Amargosa  Desert,  in  the  foothills  of  the  north 
end  of  the  Kingston  Range,  is  found  a  coarse  breccia  or  conglomerate, 
containing  pebbles  of  brown  or  blue  fetid  limestone  and  quartzite 
similar  to  that  found  in  place  in  the  Devonian  series.  These  pebbles 
are  angular,  subangular,  or  rounded,  and  are  of  all  sizes  up  to  2  feet 
in  diameter.  They  are  cemented  by  a  coarse,  red  matrix,  probably 
chieflj^  derived  from  the  limestone.  The  stratification  is  hardly  trace- 
able, 3^et  the  deposit  is  probably  water-laid.  The  general  dip  seems 
to  be  a  few  degrees  northeast.  About  two  miles  west  of  here  there 
occurs  a  thick  deposit  of  medium  coarse  granitic  arkose,  which  becomes 
finer  grained  and  changes  to  greenish  sand.  Farther  west  this  sand 
is  seen  to  overlie  a  series  of  soft  gray-green  shales,  sandstones,  and 
granitic  arkoses,  moderately  well  hardened.  The  strike  of  this  series 
is  north  and  south  and  the  dip  15°  E.  The  finer  strata  show  oscilla- 
tion ripple  marks,  such  as  are  formed  in  standing  water,  a  few  inches 
apart.  Somewhat  farther  west,  in  the  same  series,  was  found  a  pure 
white,  compact  rock,  which  microscopic  investigation  shows  to  be  a 
consolidated  volcanic  ash.  It  consists  of  many  fragments  of  glass  in 
a  white  opaque  dust  matrix.  The  ash  underlies  greenish,  considerably 
indurated,  sandstones,  often  oxidized  to  a  red  color. 

This  detrital  series  resembles  the  series  of  shales,  tuffs,  and  sand- 
stones exposed  near  Columbus  and   Silver  Peak,  which  have  been 


SPDRR]  KINGSTON    RANGE.  199 

described  by  Mr.  Turner  under  tlie  name  of  the  Esmeralda  formation, 
and  which  carry  earl}^  Tertiary  fossils.  The  series  is  also  probably 
the  same  as  that  which  makes  up  part  of  the  Funeral  Range,  and 
extends  over  so  wide  a  region  south  of  here.  Like  all  these  beds,  it  is 
probably  early  Tertiarj^ 

Mr.  R.  B.  Rowe  noted  that  about  Resting  Springs  there  are  Tertiary 
deposits  3^ounger  than  the  lavas  of  the  same  region. 

IGNEOUS    ROCKS. 

The  Tertiary  arkoses  described  above  seem  to  indicate  the  existence 
of  granite  somewhere  in  the  vicinity.  As  viewed  from  Pahrump  Val- 
ley, the  southern  portion  of  the  Kingston  Range  in  the  neighborhood 
of  Kingston  Peak  has  a  rugged,  massive  aspect  which  may  denote  the 
presence  of  granite.  Granite  occurs  not  far  southeast  of  here  in  the 
Clarks  Peak  Mountains,  where  it  cuts  the  Paleozoic  limestones. 

At  the  extreme  northern  end  of  those  low  outlying  mountains  which 
lie  to  the  north  of  the  Pahrump  Valley  there  appears  to  be,  as  seen 
fi'om  Pahrump  Valley,  a  portion  where  the  topography  is  low,  smooth, 
and  rounded,  contrasting  with  the  rugged,  banded,  stratified  rocks 
farther  south.     This  more  monotonous  region  is  probably  volcanic. 

Mr.  Rowe  noted  the  following  concerning  the  igneous  rocks  subse- 
quent to  writing  the  above : 

North  of  Resting  Springs  the  Cambrian  rocks  are  covered  by  lavas, 
which  are  separated  from  the  underlying  rocks  by  an  erosion  interval, 
but  are  folded  to  about  the  same  extent.  These  lavas  dip  at  a  high 
angle  and  are  carved  by  erosion,  like  the  sedimentary  rocks.  Thej- 
do  not  appear  to  be  as  recent  lavas  as  those  in  the  Tertiary  deposits. 
They  occupy  ancient  erosion  valleys  in  the  Cambrian. 

Between  Resting  Springs  and  Tecopa  basalt  is  present  in  large 
quantities. 

Gneisses  in  the  pass  between  Sandy  and  Kingston  Peak  are  cut 
by  many  dikes.  Kingston  Peak  itself  has  a  central  core  of  probably 
pre-Cambrian  or  basal  granite.  The  overlying  quartzite  is  cut  by 
dark-colored  igneous  rocks. 

STRUCTURE. 

According  to  Mr.  R.  B.  Rowe,  the  general  structure  of  the  Kings- 
ton Range  seems  to  be  monoclinal,  the  dip  being  to  the  east.  At 
Kingston  Peak  the  Cambrian  strata  which  overlie  the  central  core  of 
granite  dip  to  the  north  and  are  folded. 

A  sketched  cross  section  of  the  range  north  of  the  road  between 
Sandy  and  Kingston  Peak  seems  to  indicate  a  slight  synclinal  struc- 
ture at  this  point.     There  is  also  a  great  deal  of  faulting  here. 

At  Kingston  Peak  there  is  considerable  faulting  at  right  angles  to 
the  strike  of  the  rocks,  and  some  parallel  to  the  strike.  The  pass 
east  of  Resting  Springs  seems  to  be  along  a  transverse  fault. 


I 


200  GEOLOGY    Ot"    NEVADA   SOUTH    OF    40TH    PAEALLEL.     [bull. 208. 

About  8  miles  east  of  Resting-  Springs,  and  about  2  miles  northeast 
of  the  pass,  is  a  normal  fault  running  20  degi-ees  west  of  north.  This 
fault  is  also  shown  in  the  Resting  Springs  Valley.  It  brings  up  the 
Lower  Cambrian  shales  and  sandstones  against  the  overljdng 
limestone.  The  writer^'  has  estimated  the  throw  of  the  fault,  from 
Mr.  Rowe's  description,  to  be  about  8,000  feet. 

There  is  an  apparent  unconformity  at  this  place  between  the  lower 
Cambrian  and  the  overlying  limestone.  The  limestone  strikes  N.  28° 
W,,  and  dips  43°  NE. 

About  G  miles  north  of  Resting  Springs  the  lavas  which  lie  upon 
the  Cambrian  are  folded  to  the  same  extent  as  the  Cambrian,  botli 
dipi^ing  northeast  52°.  The  Cambrian  rocks  must  have  been  nearly 
level  at  the  time  of  the  eruption  of  the  lava,  although  eroded  to  a  con- 
siderable extent.  The  lava  flowed  over  the  eroded  region,  and  was 
deposited  in  the  vallej^s,  against  the  edges  of  the  strata.  Then  at  a 
later  period  l)otli  were  raised. 

A  section  of  a  spur  of  the  Kingston  Mountains  east  of  Resting 
Springs  shows  a  monoclinal  structure,  the  dips  being  uniformlj^  east. 
The  fault  above  mentioned  runs  nearly  parallel  to  the  range. 

OPAL   OR   CLARKS   PEAK   MOUNTAINS. 

This  is  a  small  group  of  mountains  situated  on  the  State  line 
between  Nevada  and  California,  just  soutli  of  the  southern  end  of  the 
Spring  Mountain  Range.  Its  chief  eminence  is  Clarks  Peak.  The 
mountains  are  probably  to  be  considered  as  an  extension  of  the  Kings- 
ton Range. 

Mr.  Gilbert'^  notes  that  in  these  mountains  near  Ivanpah  the  rocks 
are  chiefly  limestone,  of  which  the  age  was  not  determined.  Judging 
from  the  fact  that  the  Avhole  southern  part  of  the  Spring  Mountain 
Range  is  Carboniferous  and  that  the  Kingston  Range  is  apparently 
also  largely  composed  ,.7f  Cai'bon if erous  and  Devonian,  it  is  likely  that 
the  limestone  of  the  'Marks  Peak  Mountains  belongs  to  much  the 
same  period. 

Mr.  Gilbert  further  .otes  that  the  C(>ntral  portion  of  these  moun- 
tains is  occupied  hy  a  belt  of  granite,  cutting  obliquely  across  the 
range,  with  limestone  on  both  sides. 

ORE   DEPOSITS. 

Rich  silver  oi-es  occur  in  these  mountains,  both  in  the  limestone 
and  granite.      Farther  south  large  deposits  of  coi^per  are  reported.^ 

PANAMINT    RANGE. 

The  Panamint  Range  is  one  of  the  most  important  of  the  ranges 
auxiliary  to  the  Sierra  Nevada,  whicli  lie  in  the  belt  east  of  it  and  run 

nj,  E.  S. 

''  U.  S.  Geog  Snrv  W.  One  Hundredth  Mer.   Vol.  Ill,  p.  S:l. 

f  Wlieeler  Snrv.  Expl.  m  Nevada  and  Arizona,  War  Department,  1S71,  p.  53 


SPURR.]  PANAMINT    RANGE.  201 

northwest  and  sontheast  parallel  to  its  front.  The  range  is  abont  130 
miles  in  length.  At  its  northern  end  it  merges  into  lava  flows  which 
unite  it  with  the  northern  end  of  the  Grapevine  Range,  while  at  its 
southern  end  it  passes  into  low  hills  of  Tertiaiy  strata  and  associated 
lavas  capped  by  later  basic  volcanics.  It  forms  the  southwestern 
barrier  of  Death  Valley,  which  it  fronts  with  a  steep  slope. 

This  range  has  been  verj"  little  explored  and  not  much  is  known 
concerning  its  geology.  The  detail  of  its  mapping,  therefore,  and 
especially  the  differentiation  of  the  Paleozoic  which  is  known  to  exist 
in  its  central  i^ortion  into  the  Cambrian  and  Silurian  (as  has  been 
done  on  the  accompanying  map,  PI.  I),  is  very  hypothetical. 

SEDIMENTARY   ROCKS. 

CAMBRIAN. 

On  the  east  front  of  the  range,  above  the  road  from  Furnace  Creek 
in  Death  Valley  to  the  crossing  of  the  range  at  Windy  Gap  or  Win- 
gate,  a  large  portion  of  the  range  consists  of  older  stratified  rocks, 
which  seem,  as  viewed  from  a  distance,  to  lie  beneath  upturned  Ter- 
tiary sediments  and  associated  volcanics,  and  are  cut  through  by 
masses  of  intrusive  granite.  No  close  examination  of  these  older 
rocks  was  made,  but  the  drift  shows  them  to  be  in  part  finely  crystal- 
line blue  limestone,  and  in  x)art  quartzite,  white,  gray,  or  green,  often 
considerably  altered  and  often  coarse  grained.  The  amount  of  quart- 
zite in  the  drift  implies  a  considerable  thickness  of  this  rock  and 
suggests  that  the  strata  are  of  Cambrian  age,  as  this  is  the  onlj^  divi- 
sion of  the  Paleozoic  in  this  region  which  contains  great  amounts  of 
quartzite. 

From  this  neighborhood  northward  the  Panamint  Range  is  com- 
posed chiefly  of  old  Paleozoic  stratified  rocks  till  near  its  northern 
end,  as  can  be  plainly  seen  from  Death  Vallej".  On  the  accomi^anj^- 
ing  map  Cambrian  rocks  are  represented  as  running  along  the  crest 
of  the  range,  the  flanks  being  occupied  by  Silurian. 

The  Panamint  Range  has  been  examined  by  Mr.  II.  W.  Fairlianks'^ 
for  some  distance  north  of  the  region  crossed  b}^  the  writer.  Mr. 
Fairbanks  found  on  the  western  side  of  the  range,  north  of  Windy 
Gap  as  far  as  the  Pinto  Range  (whicli  is  a  spur  of  the  Panamint 
Range  running  northwesterly  from  the  Wild  Rose  mining  district), 
that  a  large  portion  of  the  rocks  are  mica- schists,  quartzites,  and 
marbles,  which  have  been  cut  by  intrusive  granite.  According  to  Mr. 
Fairbanks,  the  Pinto  Range,  as  viewed  from  the  Argus  Range,  appears 
also  to  be  formed  of  bands  of  marble  of  various  colors. 

In  the  Grapevine  Range  at  Boundary  Canyon  Mr.  Gilbert  ^  f oiind 
limestones  containing  imperfect  Cambrian  fossils.  lie  notes  that  in 
that  part  of  the  Panamint  Range  which  lies  opposite  Boundary 
Canyon  the  rocks  appear  from  a  distant  view  to  be  similar. 


"Notes  on  the  geology  of  eastern  California:  Am.  Geol.,  Vol.  XVII,  1896,  p.  63. 
6U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer. ,  Vol.  Ill, p.  33, 169, 181. 


202  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

The  strike  of  the  folds  is  parallel  with  the  trend  of  the  range,  so 
that  unless  disturbed  by  cross  faulting  the  same  general  formations 
will  be  found  for  many  miles.  Therefore  the  Cambrian  and  Silurian 
have  been  represented  on  the  map  as  extending  northward  until 
covered  by  volcanic  flows  at  the  northern  end  of  the  range. 

SILURIAN   AND   CARBONIFEROUS. 

Mr.  F.  B.  Weeks,  of  the  U.  S.  Geological  Survey,  visited  various 
parts  of  the  range  in  1900.  Near  Panamint  he  found  quartzite  and 
limestones  which  he  referred  on  stratigraphic  grounds  to  the  Cam- 
brian. South  of  Shaw  Peak  (near  the  northern  end  of  the  range)  he 
found  a  considerable  extent  of  Silurian  rocks,  with  Lower  Silurian 
(Pogonip)  fossils,  as  subsequently  determined  by  Mr."Ulrich.  South 
of  here  the  Silurian  Pogonip  formation  was  succeeded  by  the  over- 
lying Eureka  quartzite,  and  still  farther  south  were  the  Upper 
Silurian  limestones,  making  the  Silurian  belt  extend  to  Cottonwood 
Canyon.  At  the  mouth  of  Cottonwood  Canyon  Mr.  Weeks  found 
Carboniferous  fossils — Productus,  crinoid  stems,  and  a  species  of 
Serainula  {?) . 

EARLY   TERTIARY. 

The  eastern  flanks  of  the  range  fronting  Death  Valley,  as  seen  on 
the  road  between  Furnace  Creek  and  Windy  Gap,  are  composed  of 
upturned,  j^ellow-green  strata  and  associated  volcanics  lying  upon 
the  older  rocks  with  no  evident  unconformity,  and  partaking  of  their 
folds.  This  belt  of  interbedded  volcanics  and  sediments  grows  wider 
toward  the  south,  and  soon  completely  covers,  the  Paleozoic  area, 
which  is  wedged  out  between  the  younger  series  and  the  granite. 
The  same  series  occurs  along  a  great  part  of  the  road  which  crosses 
the  range  to  Windy  Gap.  It  consists  of  layers  of  calcareous  tufa, 
evidently  chemical  deposits,  with  brown  conglomerates  containing 
lava  bowlders,  interstratified  with  and  covered  by  lava,  lava  conglom- 
erate, and  lava  breccia.  The  lava  in  these  belts  proved,  in  three 
different  samples,  to  be  biotite-hornblende-andesite. 

This  series  of  conglomerates,  breccias,  tufiis,  chemical  precipitates, 
and  lavas  is  the  same  as  that  exposed  on  the  ojDposite  side  of  Death 
Valley,  where  it  forms  practically^  the  whole  mass  of  the  Funeral 
Mountains.  In  the  Funeral  Mountains  these  rocks  have  been  pro- 
visionally correlated  with  the  Esmeralda  formation  in  the  Silver  Peak 
Range,  which  are  chiefly  Eocene-Miocene. 

LATE   TERTIARY. 

Mr.  H.  W.  Fairbanks  notes"  that  on  the  northern  slopes  of  the 
Panamint  Range,  overlooking  Mesquite  Valley,  there  are  large  areas 
of  gravels,  which  are  unconsolidated  and  reach  an  elevation  of  6,000 
feet,  extending  nearly  to  the  summit  of  the  range.     These  may  be 

aAm.GeoL.Vol.  XVIl,1896,p.71. 


SPURR.]  PANAMINT    RANGE.  203 

comparable  to  the  j^onnger  semi-iudurated  conglomerate  series  in 
the  Funeral  Range,  which  is  probablj^  late  Tertiary/'  or  may  be  even 
Pleistocene. 

PLEISTOCENE, 

At  the  foot  of  the  range,  above  Death  Valley,  at  its  southern 
end,  one  finds,  overlying  unconformably  the  Tertiary  deposits  just 
described,  bluffs  of  well-rolled  pebbles  and  small  bowlders  with  per- 
fectly horizontal  stratification,  the  strata  making  a  continual  angle 
with  the  slight  dip  of  the  surface  to  the  east.  This  horizontalitj^  sug- 
gests that  the  deposit  is  a  lake  deposit,  and  connects  it  with  similar 
conglomerates  observed  in  a  similar  position  in  the  lower  part  of 
Furnace  Creek,  in  the  Funeral  Mountains.  These  conglomerates  are 
also  intimately  connected  with  the  gravels  which  occupy  the  bottom 
of  Death  Yalley  and  with  the  salt  desert  which  occurs  between  the  two 
localities  just  described. 

IGNEOUS   ROCKS. 


In  the  southern  portion  of  the  range  the  core  of  the  mountains  for 
some  distance  is  made  up  of  a  body  of  massive  granite,  which  varies 
to  g•ranite-porph5^r5^  This  granite  appears  to  be  intrusive  into  the 
Paleozoic  rocks,  but  not  into  the  Tertiaries.  Along  the  road  which 
crosses  the  range  east  of  Windy  Gap  the  granite  is  hidden  beneath 
these  Tertiary  rocks,  but  just  south  of  the  road  another  patch  of 
granite  is  exposed  around  Granite  Peak.  The  rock  at  Granite  Peak 
was  shown  by  microscopic  examination  to  be  a  biotite-granite,  verging 
toward  alaskite,  while  farther  north  two  samples  of  granite  proved  to 
be  biotite-granite-porphyry. 

Farther  north,  according  to  Mr.  Fairbanks,^  the  granite  which  cuts 
the  ancient  limestones  and  quartzites  in  the  mining  regions  on  the 
east  side  of  Panamint  Vallej^  is  a  biotite-hornblende-granite  with 
much  quartz. 

VOLCANIC   ROCKS. 

As  already  stated,  volcanic  rocks  make  up  a  considerable  portion 
of  the  Tertiary  formations.  Three  specimens  of  these  rocks  examined 
all  proved  to  be  biotite-  or  hornblende-andesite,  but  probably  other 
rocks  occur  in  the  series. 

Overljang  these  folded  lavas  unconformably  is  a  later  flow  of  more 
basic  rock,  which  covers  a  considerable  area  in  the  neighborhood  of 
Browns  Peak,  just  south  of  Windy  Gap.  Two  specimens  of  this  rock 
taken  at  different  places  proved  to  be  in  one  ease  pyroxene-aleutite, 
and  in  the  other  bronzite-olivine-aleutite.^  Analysis  shows  them  to 
be  rather  siliceous  for  the  species. 

aSee  p.  191. 

&Ani.  Geol.,  Vol.  XVH,  1896,  p.  72. 

cSee  J.  E.  SpuiT,  Am.  Geol.,  Vol.  XXV,  p.  333.  Aleutite  is  transitional  between  andesite  and 
basalt. 


204         GEOLOGY    OF    JSTEVADA  SOUTH    OF   40TH    PARALLEL,     [bull. 208. 

Mr.  H.  W.  Fairbanks  states'^'  that  ou  the  northern  slopes  of  the 
Panamint  Range,  overlooking  Mesquite  Vallej^,  there  are  scattered 
sheets  of  andesite  and  basalt. 

Yet  another  sei'ies  of  volcanics  is  exposed  in  this  region.  It  is  that 
forming  the  greater  part  of  the  Slate  Range,  which  lies  immediately 
west  of  the  sonlhern  end  of  the  Panamint  Range.  The  same  rocks 
o^cur  in  the  region  south  of  Browns  Peak,  in  the  Panamint  Range, 
underljdng  the  aleutites.  These  older  volcanics  are  comparatively 
light  colored  and  weathei'  reddish ;  they  are,  moreover,  considerably 
sheared.  Thin  sections  fail  to  exactly  determine  their  nature,  except 
that  the}^  are  really  lavas  with  glassy  groundmass,  and  that  they  are 
largely  feldspathic.  From  the  shearing  it  is  jirobablethat  these  lavas 
are  older  than  those  in  the  folded  Tertiar3^  series. 

Mr.  Fairbanks^  found  forming  the  highest  portion  of  the  Panamint 
Range  for  a  number  of  miles  east  of  Panamint  a  body  of  ancient 
rhyolite,  which  he  regards  as  one  of  the  most  ancient  lavas  observed 
in  the  region. 

According  to  Mr.  F.  B.  Weeks,  of  the  United  States  Geological  Sur- 
vey, who  has  visited  the  northern  end  of  the  Panamint  Range,  the 
Paleozoic  rocks  are  here  covered  by  extensive  flows  of  lava,  which 
appear  to  be  nearlj^  continuous  with  the  lava  area  at  the  extreme 
southwestern  end  of  the  Silver  Peak  Range. 

STRUCTURE. 

That  portion  of  the  Panamint  Range  between  a  point  opposite  Fur- 
nace Creek  and  Windy  Gap  api^eared  to  the  writer,  studjang  it  through 
field  glasses,  to  be,  in  general,  anticlinal.  From  Cottonwood  Canyon 
northward  to  Shaw  Peak,  according  to  Mr.  F.  B.  Weeks,^  the  Pale- 
ozoic strata  dip  in  general  north  of  west. 

The  Paleozoic  and  Tertiary  strata  on  the  east  side  of  the  range, 
south  of  Emigrant  Canyon,  are  apparently  conformable  and  have  the 
same  folds.  There  is  here  a  series  of  alternating  anticlines  and  syn- 
clines,  having  trends  due  north  and  south.  Each  of  these  folds  maj^ 
be  traced  continuouslj^  for  a  number  of  miles.  The  axes  of  the  folds, 
as  sketched  on  the  map,  form  a  series  of  straight  lines  of  moderate 
length,  tiie  more  southern  of  which  are  continually^  offset  to  the  east 
from  the  more  northern  ones.  The  explanation  of  this  phenomenon 
may  be  a  series  of  east-west  faults,  which  fault  the  folds  system- 
aticall}^  to  the  east  on  the  south  side. 

Just  north  of  the  eastern  part  of  the  road  which  runs  from  Furnace 
Creek  to  Windy  Gap,  where  this  road  enters  the  Panamint  Range, 
the  strike  of  the  folds  changes  from  north  and  south  to  northwest  and 
southeast,  and  so  continues  to  the  extreme  termination  of  the  range, 
in  the  neighborhood  of  Owlshead  Peak.  In  all  this  extreme  southern 
portion  there  are  no  Paleozoics,  but  the  Tertiary  interbedded  sedi- 


« Letter  to  the  writer.  ''  Am.  Geol.,  Vol.  XVII,  1896,  p.  73.  ''Oral  communication. 


SPUHR.]  LEACH    POINT    AND    BURNT    ROCK    MOUNTAINS.  205 

ments  and  lavas  .show  the  same  system  of  folding  as  in  the  Paleozoics, 
altlioiigh  somewhat  less  pronouuced. 

The  Pluto  Mountains,  a  spur  of  the  Panamiut  Range,  lying  north- 
east of  the  "Wild  Rose  mining  district,  are  stated  by  Mr.  Fairbanks'* 
to  have  an  apparent  monoclinal  structure,  exposing  an  enormous 
thickness  of  strata  whose  truncated  edges  face  Panamiut  Yalley. 

In  tlie  Panamiut  Range  much  of  the  deformation  must  be  of  com- 
paratively recent  date.  AVe  know  that  much  of  it  occurred  since  the 
deposition  of  the  Tertiary  beds  and  associated  lavas,  since  these  are 
involved  with  the  Paleozoics  in  the  upturning". 

ORE    DEPOSITS. 

The  following  brief  note  on  the  ores  of  the  Panamiut  Range  is 
gleaned  from  the  reports  of  Mr.  H.  W.  Fairbanks.*  Near  Postof&ce 
Springs  gold  is  found  in  quartz  veins  inclosed  in  limestone,  which  is 
folded  to  a  syncline,  with  slates  below  and  on  both  sides.  The  ore  is 
high  grade.  In  the  neighborhood  of  the  old  town  of  Panamiut  are 
found  silver-bearing  sulphides  of  copper,  antimony,  and  arsenic, 
sti'omeyerite  and  tetrahedrite  being  the  most  common  minerals.  The 
gangue  of  the  veins  is  quartz,  and  the  veins  are  found  in  all  the  sed- 
imentary formations  of  the  district.  North  of  here,  in  the  Wild  Rose 
district,  a  similar  class  of  ores  is  found.     Galena  is  seldom  observed. 

LEACH   POINT   AND   BURNT   ROCK   MOUNTAINS. 

The  roughly  defined  east-west  chain  of  low,  irregular  mountains 
which  stretches  eastward  from  the  southern  end  of  the  Sierra  Nevada 
at  El  Paso  Peak  to  Pilot  Knob  is  continued  farther  east  in  other  Ioav, 
irregular  mountains,  which  just  east  of  Pilot  Knob  have  been  called 
the  Burnt  Rock  Mountains,  and  still  farther,  in  the  same  direction,  the 
Leach  Point  Mountains.  On  the  north  of  these  mountaius  the  narrow 
Leach  Point  Yallej^  separates  them  from  the  southern  end  of  the  Pan- 
amiut Range.     On  the  south  lies  the  Mojave  Desert. 

SEDIMENTARY    ROCKS. 

LIMESTONE. 

About  8  miles  northeast  of  Pilot  Knob  there  occurs,  along  the 
main  traveled  road,  an  outlying  spur  from  the  low  mountains,  which 
is  composed  of  very  sandy  blue  limestone,  amounting  almost  to  a 
graj^  ciuartzite.  This  is  interbedded  with  shaly  and  cherty  thin- 
bedded  limestones.  This  rock  strikes  N.  00°  E.  and  dips  E.  65°. 
It  is  slightly  altered  and  sheared,  and  no  fossils  were  found.  It  forms 
only  a  small  patch,  and  is  overlain  by  basalt. 

"Am.  Geol.,  Vol.  XVn,  1896,  p.  66. 

&  Mineral  deposits  of  eastern  California:  Am.  Geol.,  Vol.  XVII,  1896,  pp.  144,  151. 


206  GEOLOGY    OF   NEVADA  SOUTH    OF   40TH    PARALLEL,     [bull,  208. 


The  bulk  of  the  mountains  Ijang  east  of  Pilot  Knob  are  flat  topped 
and  slightly  pinnacled.  They  consist  of  light-colored  stratified  beds, 
with  intercalated  sheets  of  lava,  the  whole,  in  general,  capped  by 
black  sheets  of  basalt.  Mr.  Gilbert  '^  has  also  noted  these  deposits  in 
this  range.  They  are  probably  the  sam^  as  those  exposed  in  the 
El  Paso  Mountains,  where  they  contain  Eocene  fossils,  and  they  are 
also  the  same  as  those  which  make  up  the  Funeral  Range  and  thus  are 
widelj^  distributed  throughout  this  region. 

IGNEOUS   ROCKS. 

GRANITE. 

Along  the  western  edge  of  these  mountains  granite  is  seen  to  be 
the  basal  rock.  A  specimen  collected  a  few  miles  north  of  Pilot 
Knob  appears  to  be  a  typical  biotite-granite.  The  relation  of  this 
rock  to  the  limestone  above  described  is  not  known,  but  it  is  very 
likel}'^  intrusive  in  it,  if  we  may  judge  from  the  similar  occurrences 
in  the  Panamint  and  El  Paso  ranges  and  in  other  neighboring  ranges. 

VOLCANIC   ROCKS. 

Some  miles  north  of  Pilot  Knob  typical  tordrillite*  was  collected, 
apparently  derived  from  one  of  the  sheets  intercalated  in  the  lake  beds. 

Sheets  of  black  basalt  overlie  the  lake  beds  and  constitute  the 
latest  volcanic  rock  of  the  region. 

STRUCTURE. 

The  Tertiary  beds  and  intercalated  lava  sheets  seem  to  be,  in  gen- 
eral, nearly  horizontal,  but  in  one  place  at  least — about  4  miles  north- 
east of  Pilot  Knob — an  anticlinal  fold  was  observed,  having  a  nearly 
north-south  trend,  with  dips  of  from  10°  to  20°  on  the  limbs. 

WHITE  MOUNTAIN  RANGE. 

The  important  mountain  range  immediately  east  of  the  Sierra  has 
gone  by  the  name  of  the  White  Mountains  in  its  northern  portion  and 
the  Inyo  Range  in  its  southern.  Inasmuch  as  the  two  so-called  ranges 
are  not  in  any  way  disconnected,  but  form  a  complete  whole,  they  will 
be  here,  for  the  sake  of  convenience,  described  together  under  the  head 
of  the  White  Mountain  Range,  as  suggested  by  Mr.  Walcott.'^  The 
range  extends  in  a  northwesterly  and  southeasterly  direction,  from 
the  Candelaria  Mountains  on  the  north  to  the  neighborhood  of 
Owens  Lake  on  the  south,  passing  at  both  ends  into  lower,  irregular 
mountains  of  lava.    No  part  of  the  range  has  been  visited  by  the  writer, 

aJJ.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  HI,  p.  125. 

6  Differing  from  rliyolite  in  the  lack  of  essential  ferromagnesian  constituents.  See  J.  E.  Spurr: 
Am.  Geol.,  Vol.  XXV,  1900,  p.  230. 

cAm.  Jour.  Sci.,  3d  series,  Vol.  XLIX,  p.  169. 


SPURR.]  WHITE    MOUNTAIN    RANGE.  207 

and  the  following  notes  are  entirely  a  compilation  of  observations, 
although  now  for  the  first  time  brought  together.  The  observers 
include  Messrs.  Gilbert,  Walcott,  Turner,  and  Weeks,  of  the  United 
States  Geological  Survej'',  and  Goodyear,  Gabb,  and  other  geologists 
of  the  geological  survey  of  California. 

TOPOGRAPHY. 

As  a  rule  the  topography  of  the  White  Mountains  is  characterized 
by  great  relief,  with  deep  canyons  and  high  peaks.  On  the  eastern 
side  of  the  range  there  is  an  abrupt  scarp  for  manj'^  miles,  while  the 
western  slope,  although  generally  steep,  is  on  the  average  considerably 
gentler  than  the  eastern.  White  Mountain  Peak,  which  is  at  the 
northern  end  of  the  range,  is  of  granite,  and  is  a  conspicuous  land- 
mark for  many  miles.  It  stands  exactly  on  the  boundary  between 
Nevada  and  California. 

SEDIMENTARY   ROCKS. 
CAMBRIAN. 

Near  the  central  portion  of  the  range,  or  at  the  southern  end  of 

the  White  Mountains  proper,  Mr.  Gilbert '^  early  observed  a  series  of 

quartzites  and  schists  with  a  little  limestone.     The  age  of  this  series 

he  did  not  determine.     Later  Mr.  Walcott  investigated  it  and  found 

it  to  be  Lower  Cambrian.     Mr.  Walcott's  chief  studies  were  on  the 

western  side  of  the  range.     In  several  canyons  to  the  east  of  Big  Pine, 

namely,  Waucobi,  Black,  and  Silver  canyons,  Mr.  Walcott*  found  the 

following  section: 

Section  east  of  Big  Pine. 

Feet. 

4.  Upper  arenaceous  beds 200 

3.  Alternating  limestones  and  shales 1,000 

2.  Siliceous  slates  and  quartzites 2, 000 

1.  Siliceous  limestones . 1,  700 

Total 4,900 

No  fossils  were  found  in  the  lower  limestone,  but  in  the  lower  silice- 
ous series  are  annelid  trails  and  in  places  the  heads  of  Olenellus, 
Avhile  in  the  upper  limestone  are  great  quantities  of  Cambrian  corals, 
of  the  same  types  as  occur  in  the  Silver  Peak  Range  to  the  east. 
Mr.  Walcott  notes  that  this  is  the  oldest  Cambrian  fauna  known  in 
the  western  portion  of  the  United  States. 

Northward  from  this  locality  Mr.  Walcott  found  Cambrian  rocks 
along  the  western  face  of  the  range,  nearly  to  its  northern  end. 

On  the  eastern  side  of  the  range  he  found  many  of  the  low  moun- 
tains lying  northeast  of  Salinas  Valley^  to  be  Cambrian,  and  also  a 

all.  S.  Geog.  Surv.  W.  One  Hundredtli  Mer.,  Vol.  ni,  p.  169. 
6Am.  Jour.  Sci.,  3d  series,  Vol.  XLIX,  1895,  pp.  141-144. 
c Personal  communication  to  the  writer. 


I 


208  GEOLOGY    01'    NEVADA   SOUTH    OF    40TH    PAHALLEL.     [bull.208. 

great  part  of  the  main  White  Mountain  Range  bordering  the  same 
valley  on  the  west.  At  the  latter  locality  Cambrian  rocks  are  cut  by 
great  masses  of  intrusive  granite.  At  the  northern  end  of  the  range 
Cambrian  rocks  occur  in  considerable  quantities  on  the  eastern  side, 
alternating  with  areas  of  granite  which  are  intrusive  into  them." 

The  rocks  have  here  suffered  considerable  contact  metamorphism 
bj^  the  granite,  the  limestones  being  sometimes  changed  to  dolomitic 
marbles. 

SILURIAN. 

Mr.  Walcott*  discovered  a  patch  of  rocks  bearing  Silurian  (Trenton) 
fossils  on  the  eastern  side  of  the  range,  southeast  from  Big  Pine,  along 
the  road  leading  from  Waucobi  Canyon. 

Mr.  F.  B.  Weeks*  found  in  1900,  near  the  head  of  Mazurka  Canyon, 
rolled  remains  of  crinoids  and  fragments  of  biyozoa  which  indicate 
that  the  rocks  at  this  place  are  not  older  than  Middle  Ordovician, 
and  may  be  somewhat  younger. 

At  the  southern  end  of  the  range,  in  the  vicinity  of  Cerro  Gordo, 
Dr.  O.  Loew^'  reports  that  the  rocks  are  largely  Silurian  limestones 
containing  great  numbers  of  fossils,  whose  genera  and  species,  how- 
ever, he  does  not  record.  These  rocks,  he  notes,  are  cut  into  by 
intrusive  masses  of  granitic  rocks. 

CARBONIFEROUS. 

Mr.  Walcott'^  records  that  Mr.  Fairbanks,  of  the  California  Mining 
Bureau,  discovered  the  characteristic  Coal  Measures  fossil,  F'usuliiia 
cyUndrica,  in  the  southern  end  of  the  range  east  of  Keeler. 

Also  at  the  southern  end  of  the  range,  just  below  the  summit  of 
Cerro  Gordo  Peak  the  follow^ing  Carboniferous  fossils  were  found  by 
Mr.  Weeks  in  1900,  and  were  determined  by  Dr.  Girty: 

Rhipidomella  ?    sp. 
Aniplexus  westi  ? 
Prodtictiis  fragments. 
Marginifera  splendens  ? 

TRIASSICi 

Just  east  of  Cami)  Independence  Dr.  Horn,  of  the  California  geo- 
logical survey,  discovered  a  fossil  in  a  series  of  slates  with  intercalated 
limestone  beds,  which  was  considered  by  Mr.  Gabb'  to  be  Triassic. 

According  to  Professor  Whitney,  these  same  slates  extend  north- 
ward from  Bend  City  (just  east  of  Camp  Independence)  for  :25  miles. 
Yet  this  general  region  is  delineated  on  the  map  accompanying  this 

nPersonal  communication  to  the  writer  by  Mr.  Turner  and  Mr.  Weeks. 

''Personal  communication  to  the  writer. 

'■Ann.  Rept.  U.  S.  Geol.  Surv.  W.  One  Hundredth  Mer.,  1876,  p.  63. 

''Am.  Jour.  Sci.,  3d  series,  Vol.  XLIX,  1895,  p.  144. 

<?Geol.  Survey  California,  Vol.  I,  1865,  p.  459. 


spuRR.]  WHITE   MOUNTAIN    RANGE.  209 

bulletin  as  granite,  following  the  preliminary  geological  maps  of  the 
State  of  California,  published  in  1891  by  the  State  Mining  Bureau. 

South  of  the  locality  above  mentioned,  near  the  crest  of  the  range, 
halfway  between  Independence  and  Owens  Lake,  Mr.  AValcotf^*  found 
a  single  block  containing  Triassic  fossils. 

Mr.  Turner'*  traced  the  Triassic  rocks  as  a  continuous  belt  between 
the  two  localities  above  mentioned  and  also  some  distance  farther 
south  along  the  western  flanks  of  the  range.  Mr.  Turner  states  that 
the  rocks  consist  essentially  of  Triassic  lavas  with  iuterbedded  tuffs. 
The  same  rocks  occur  on  the  western  side  of  Owens  Valley,  northwest 
of  Owens  Lake,  on  the  flanks  of  the  Sierras,  and  here  also  are  of  the 
same  character. 

From  the  lithology  of  the  Triassic  rocks  above  mentioned  a  proba- 
ble coi'relation  is  established  with  the  Koipato  group  of  the  fortieth 
parallel  Triassic,  as  defined  by  King. 

PLIOCENE. 

Just  east  of  Big  Pine  Mr.  Walcott^  has  described  a  considerable 
area  covered  by  consolidated  stratified  deposits,  which  he  regards  as 
lake  beds.  The  strata  consist  of  fine  calcareous,  arenaceous,  and 
argillaceous  sands  with  layers  of  fine  conglomerate,  the  whole  being 
covered  by  angular  debris  washed  down  from  the  mountain  since  the 
deposition  of  the  stratified  material.  The  deposits  are  coarser  near 
the  mountains  and  finer  as  the  distance  increases.  Some  of  the  white 
beds  are  made  up  almost  entirelj^  of  fresh-water  shells,  concerning 
which  Dr.  Dall  says:  "Anj^  of  them  may  be  recent  or  Pliocene.  My 
imjjression  from  the  mass  is  that  they  are  Pleistocene."  Mr.  Walcott^ 
found  these  beds  reaching  from  the  bottom  of  the  valley  up  to  a  height 
of  3,000  feet  above  the  valley,  or  to  an  actual  height  above  sea  level 
of  about  7,000  feet.  As  an  explanation  for  the  great  height  at  which 
these  deposits  are  found,  Mr.  Walcott  mentions  two  main  hypoth- 
eses— first,  that  a  lake  3,000  feet  deep  existed  over  the  site  of  the 
present  Owens  Lake,  and,  second,  that  the  Inyo  or  White  Mountain 
Range  has  been  elevated  since  the  deposition  of  the  lake  beds,  carry- 
ing up  these  beds  with  it.  He  inclines  to  the  view  that  the  latter  is 
the  correct  hypothesis,  on  account  of  the  steep  easterly  scarp  of  the 
range,  which  might  be  taken  as  a  fault  scarp,  and  from  other  consid- 
erations. * 

The  character  of  these  beds,  as  described  by  Mr.  Walcott,  and  their 
nearly  horizontal  attitude  are  identical  with  those  of  deposits  of  the 
late  Pliocene  lake  which  has  already  been  described  by  the  writer  as 
observed  by  him  in  numerous  localities  in  Nevada,  but  chiefly  in  the 
region  between  Lake  Mono  and  Carson.  All  these  beds  he  has  con- 
sidered as  the  deposits  of  a  late  Pliocene  lake— the  Lake  Shoshone  of 

a  Personal  communication  to  the  writer.       l>  Jonr.  Geol.,  Vol.  V,  p.  340.        i^  Ibid.,  p.  345. 

Bull.  208—03 1-1 


210  GEOLOGY    OF   NEVADA   SOUTH    OF   40TH    PARALLEL,    [bull. 208. 

King."  In  the  region  just  nortli  of  Lake  Mono  he  found  the  highest 
deiDOsits  of  this  lake  at  an  altitude  of  7,100  feet,  and  came  to  the  con- 
clusion that  the  uppermost  deposits  of  the  ancient  Lake  Mono  formed 
part  of  the  deposits  of  the  same  great  water  body.  When  the  great 
lake  stood  at  this  altitude  it  must  have  been  connected  by  numerous 
straits  with  the  valley  of  the  present  Owens  River,  which  formed  an 
arm  of  the  same  lake.  The  uppermost  limit  of  the  lake  beds  noted  by 
Mr.  Walcott  coincides  almost  exactly  with  the  uppermost  limit  in  the 
vicinity  of  Lake  Mono  and  to  the  north  of  it.  It  is  therefore  likely 
that  the  deposits  on  the  slopes  of  the  White  Mountain  Range  are  to 
be  correlated  with  these  other  deposits.  The  age  indicated  by  the 
fossils  found  by  Mr.  Walcott  also  coincides  with  the  other  determina- 
tions made  in  other  localities,  all  combining  to  indicate  a  period 
between  late  Pliocene  and  early  Pleistocene. 

If  this  is  the  case,  no  local  elevation  of  the  Wliite  Mountains  can  be 
inferred  from  the  position  of  the  lake  beds  at  the  comparatively  great 
altitude  where  they  are  found,  since  the  altitude  is  similar  over  the 
whole  region.  As  was  inferred  by  the  writer  with  reference  to  the 
region  around  Lake  Mono,  there  appears  to  have  been  a  general  uplift 
of  mountain  and  valley  throughout  this  whole  region,  lifting  the 
deposits  of  the  Pliocene  lake  about  1,000  feet  higher  than  farther 
north. 

South  of  Owens  Lake  Mr.  Turner  found  *  well-stratified  sands, 
gravels,  and  tuffs,  occupying  a  large  portion  of  the  valley  beneath 
the  overlying  Pleistocene  accumulations,  and  having  a  slight  dip  west- 
ward. These  may  belong  to  the  same  series  as  above  described.  The 
same  beds  are  mentioned  by  Mr.  Fairbanks,'^  who  notes  that  at  Owens 
Lake  they  reach  an  elevation  of-  at  least  1,500  feet  above  the  lake 
surface.     Mr.  Fairbanks  regards  these  beds  as  formed  under  water. '^ 

IGNEOUS   ROCKS. 
GRANITIC   ROOKS. 

Mr.  Gilbert  ^  noted  that  the  eastern  ridge  of  the  White  Mountains, 
east  of  Deep  Springs  Valley,  is  composed  of  granite.  The  map  of  the 
California  State  Mining  Bureau-^  shows  a  number  of  other  granite 
areas.  On  this  map  the  whole  northern  end  of  the  range  in  the  vicin- 
ity of  White  Mountain  Peak  is  shown  to  be  of  granite,  and  also  most 
of  the  range  from  Loehr  Peak  southward  to  Deep  Springs  Valley. 
Farther  south,  a  considerable  area  of  granitic  rocks  is  shown  south  of 

a  See  pp.  117, 119, 1S3. 

&  Personal  comrmmication. 

(■Am.  GeoL,  Vol.  XVII,  p.  69. 

f'Mr.  M.  B.  Campbell's  later  notes  on  these  gravels  (Bull.  U.  S.  Geol.  Survey  No.  200,  p.  20)  show 
that  they  are  gently  folded  lake  sediments  containing  much  volcanic  tuff.  They  are  very  likely 
pre-Pliocene  (Eocene  or  Miocene),  like  the  lake  beds  in  Funei-al  Range. 

eV.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  315. 

/Preliminary  mineralogical  and  geological  map  of  the  State  of  California,  1891. 


SPURR]  WHITE    MOUNTAIISr    RANGE.  211 

Waucoln  Peak,*^  while  a  small  area  is  shown  southwest  of  Salinas  Val- 
lej^,  also  in  the  center  of  the  range.  In  the  low  monntains  lying 
northeast  of  Salinas  Valley  two  considerable  areas  are  shown. 

From  personal  commnnications  of  Messrs.  Walcott,  Turner,  and 
Weeks,  further  information  on  the  extent  of  the  granite  has  been 
obtained.  The  two  northern  granite  areas  represented  as  separate 
on  the  above-cited  map  appear  to  be  continuous  between  Loehr  Peak 
and  White  Mountain  Peak.  On  the  eastern  side  of  the  northern  end  of 
the  range  a  great  deal  of  granitic  rock  is  found,  cutting  bhe  Cambrian 
sediments.  Farther  south,  the  granite  area  south  of  Waucobi  Peak 
extends  sontheastward  in  a  continuous  belt  to  the  area  southwest  of 
Salinas  Valley,  and  the  Cambrian  beds  west  of  Salinas  Valley  are  cut 
through  by  juasses  of  the  same  rock. 

VOLCANIC   ROCKS. 

As  noted  above,  many  of  the  Triassic  rocks  are  lavas.  There  are, 
moreover,  some  areas  of  Tertiary  and  Pleistocene  lavas^  as  repre- 
sented on  the  map.  Mr.  Gilbert  ^  noted  some  basalt  just  east  of  Big 
Pine.  The  map  of  the  California  Mining  Bureau,  above  mentioned, 
shows  an  area  of  volcanic  rocks  lying  on  the  west  flanks  of  the  range 
in  the  neighborhood  of  Waucobi  Peak,  and  connecting  westward 
across  Owens  Vallej^  with  a  larger  area  of  lava  on  the  eastern,  slopes 
of  the  Sierra.  The  same  map  also  shows  volcanic  rocks  lying  on  the 
northern  slopes  of  the  granite  of  White  Mountain  Peak,  at  the  north- 
ern end  of  the  range,  and  shows  a  great  area  of  lava  lying  southeast 
of  Owens  Lake,  and  forming  the  southern  end  of  the  range.  Mr. 
Turner  found  that  the  mountains  east  of  Sandy  Springs,  which  form 
a  kind  of  connection  between  the  northern  end  of  the  White  Mountain 
Range  and  the  Silver  Peak  Range,  are  mostly  volcanic. 

ORE    DEPOSITS. 

The  following  notes  are  taken  from  Mr.  H.  W.  Fairbanks's  writings.  ^ 
Silver-lead  ores,  chiefly  in  limestone,  are  found  about  Cerro  Gordo 
and  southeast  of  Independence. 

Auriferous  quartz  veins  are  abundant.  They  are  found  north  of 
Cerro  Gordo,  in  the  Beveridge  district,  in  the  Alhambra  Hills,  5  miles 
north  of  Lone  Pine,  between  Independence  and  Big  Pine,  and  east 
and  northeast  of  Bishop  Creek.  The  veins  are  chiefly  in  or  near 
granite,  often  at  or  near  the  contact  of  it  with  slates  or  limestones. 
They  probablj^  have  a  genetic  connection  with  the  granitic  intrusion. 

<i According  to  Professor  Whitney,  however  (Geological  Survey  of  California,  Geology,  Vol.  I, 
p.  459),  the  western  face  of  the  range,  south  of  Waucobi  Peak  to  Bend  City  (just  east  of  Camp 
Independence),  is  composed  of  tilted  slates  and  other  stratified  rocks.  If  this  is  the  case,  these 
stratified  rocks  are  undoubtedly  continuous  with  the  Triassic  rocks  south  of  Camp  Inde- 
pendence. 

&U.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  124. 

c Report  California  Min.  Bureau,  1S94,  p.  475;  Am.  GeoL,  Vol.  XVII,  No.  3,  pp.  14.5, 146,  149,  150. 


212  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PAKALLEL.     [bull. 308. 

STRUCTURE. 

Mr.  Gilbert^  gives  a  cross  section  of  the  range  east  of  Big  Pine, 
which  exhibits  several  adjacent  folds  of  moderate  dip,  broken  by  a 
number  of  faults.  According  to  Mr.  Gilbert's  section  the  faults  are 
not  directly  expressed  in  the  topography. 

Later  Mr.  Walcott  *  described  several  sections  of  the  White  Moun- 
tain Range,  in  the  same  general  region  as  that  in  which  Mr.  Gilbert's 
section  was  made.  Mr.  Walcott  also  finds  the  range  made  up  of  a 
number  of  adjacent  folds  broken  by  faults,  and  finds  the  chief  fold  to 
be  a  closely  compressed  syncline  overthrown  to  the  east,  thus  present- 
ing a  type  of  structure  common  in  the  Appalachians. 

DARWIN  OR  ARGUS  RANGE. 

This  range  is  low  and  of  no  great  importance.  It  lies  between  the 
Panamint  Range  and  the  Coso  Mountains  and  is  south-southeast  of  the 
White  Mountain  Range.  The  range  is  about  70  miles  in  length  and 
very  narrow.     Through  its  northern  portion  Darwin  Canyon  runs. 

SEDIMENTARY   ROCKS. 

Mr.  H.  W.  Fairbanks^  notes  that  the  eastern  face  of  the  Argus 
Range,  from  Darwin  to  Modoc,  is  made  up  largely  of  limestone,  which 
sometimes  forms  the  crest  of  the  range  and  is  present  in  great  thick- 
ness.    Besides  the  limestone  there  is  also  calciferous  quartzite. 

The  age  of  this  Paleozoic  series  is  not  known,  but  it  is  provisionally 
mapped  as  Cambrian,  in  view  of  the  probable  age  of  the  rocks  of  the 
Panamint  Range  to  the  east.^ 

IGNEOUS   ROCKS. 


According  to  Mr.  Fairbanks,^  granite  occupies  a  considerable  por- 
tion of  the  Argus  Range,  forming  part  of  a  continuous  body  which 
stretches  from  the  Mojave  Desert  to  the  Sierra  Nevada.  In  general, 
it  is  a  granular,  light-colored,  biotite-hornblende  rock. 

VOLCANIC   ROCKS. 

From  Darwin  Canyon  north  to  the  36°  30'  parallel  the  mountains 
are  described  as  black  lava  hills  on  the  topographic  map  of  the 
Wheeler  Survey  (65-D).  This  same  portion  of  the  range  is  also  rep- 
resented as  volcanic  on  the  preliminary  geologic  map  of  California, 

«U.  S.  Geog.  Surv.  W.  One  Hundredth  Mei-..  Vol.  Ill,  p.  34. 

6Am.  Jovr.  Sci.,  .3d  series,  Vol.  XLIX,  1895,  p.  169 

cAm.  Geol.,  Vol.  XVII,  1896,  pp.  65,  149. 

rfSince  writing  the  above  Mr.  F.  B  Weeks  has  informed  the  writer  that  in  1900  he  fodnd  in 
Shepherd  Canyon  heavy  exposures  of  quartzite  overlain  by  limestone,  which  he  had  no  hesita- 
tion in  referring  on  stratigraphic  grounds  to  the  Cambrian. 

«Op.  cit.,  p.  72. 


SPURR.]  DARWIN    AND    SLATE    RANGES.  213 

issued  hj  the  California  mining  bureau  in  1891.  On  this  maj)  the 
lava  is  represented  as  extending  southward  along  the  range  to  a  point 
beyond  Malurango  Peak. 

Mr.  H.  ^y.  Fairbanks"  reports  numerous  flows  of  andesite  and 
basalt  through  the  Argus  Range,  forming  inclined  plateaus  on  the 
mountain  slopes.  One  of  these  basalt  flows  is  exposed  in  Argus 
Gulch,  and  beneath  it  is  an  ancient  river  channel  flUed  with  clay  and 
gravel. 

The  southern  portion  of  the  range  has  a  volcanic  appearance,  as 
seen  by  the  writer  from  a  point  farther  south. 

ORE    DEPOSITS. 

Mr.  Fairbanks*  states  that  a  large  number  of  gold-bearing  quartz 
A^eins  are  scattered  through  the  southern  portion  of  the  Argus  Range. 
There  is  also,  in  the  neighborhood  of  Darwin  and  Modoc,  considerable 
galena,  rich  in  silver,  in  chambers  in  the  limestone. 

SLATE  RANGE. 

The  Slate  Range  lies  in  Panamint  Valley,  between  the  southern  end 
of  the  Panamint  and  that  of  the  Darwin  or  Argus  ranges.  It  has  an 
extent  of  only  about  12  miles,  and  is  comparatively  low  and  narrow. 
The  range  derives  its  name  from  the  fact  that  its  rocks  have  been 
sheared  so  as  to  assume  a  slaty  structure. 

SEDIMENTARY    ROCKS. 
PALEOZOIC. 

Mr.  H.  W.  Fairbanks  states  that  nietamorphic  strata  appear  promi- 
nently in  the  Slate  Range. 

TERTIARY. 

At  the  extreme  southern  end  of  the  range  schistose  volcanics  are 
overlain  by  cream-colored  Tertiarj^  sediments,  capped  by  later  basaltic 
lava.  These  Tertiary  sediments  are  probably  the  same  as  those 
exposed  in  the  Panamint  Range  just  east  of  here,  and  also  in  the 
Funeral  Mountains. 

IGNEOUS   ROCKS. 
VOLCANIC   ROCKS. 

So  far  as  could  be  observed,  the  range  near  Windy  Gap  and  from 
here  southward  to  the  extreme  end  consists  of  uniform  rocks.  As 
examined  under  the  microscope,  these  rocks  seem  to  be  sheared 
feldspathic  lava,  much  altered.  The  exact  nature  of  the  lava  could 
not  be  determined,  but  it  consists  chiefly  of  a  glassy  groundmass,  with 
phenocrysts  of  feldspar.  One  specimen  studied  was  so  sheared  as  to 
be  comminuted  into  bits. 

a  Am.  Geol.,  Vol.  XVH,  1896,  p.  73.  Mbid,,  pp.  145, 149. 


214  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull.208. 

The  age  of  the  schistose  volcanics  is  not  known,  except  that  thej^ 
are  older  than  tlie  basalt  and  probably  older  also  than  the  Tertiary 
sediments.  Their  shearing  suggests  a  considerable  age  and  also  sug- 
gests that  they  may  be  connected  with  the  granites  of  the  Panamint 
Range,  or  with  the  ancient  rhyolite  of  that  range  east  of  Panamint,^ 
which  rhyolite  has  a  probable  connection  with  that  in  the  vicinity  of 
Johannesburg. 

At  the  northern  end  of  the  range  the  slaty  rocks  appear  to  be  in 

part  overlain  bj^  later  volcanic  flows,  as  seen  from  the  south  end. 

There  are  probably  basalts  similar  to  those  at  the  south  end  of  the 

range. 

COSO  RANGE. 

IGNEOUS   ROCKS. 


The  central  portion  of  the  Coso  Mountains  is  made  up  of  granite 
and  gneissoidal  rocks. '^  The  rock  in  this  range  is  reported  by  Mr. 
H.  W.  Fairbanks'^  to  be  a  coarse,  easily  decomposed  granite,  and  the 
same  writer  states  that  granite  makes  up  most  of  the  rest  of  the  range. ^ 
This  granite  is  continuous  with  the  granite  of  the  Sierra  Nevada. 

VOLCANIC   ROCKS. 

Mr.  Gilbert  notes  that  the  western  base  of  Coso  Range,  south  of 
Owens  Lake,  appears  to  be  entirely  eruptive.  Mr.  Fairbanks-^  has 
noted  volcanic  rocks  belonging  to  two  distinct  periods  of  eruption  in 
the  western  part  of  the  range.  To  the  older  rocks  belong  rhyolites 
and  andesites,  while  the  younger  consist  of  extensive  flows  of  basalt 
(so  recent  in  origin  that  their  surfaces  have  been  but  slightly  modified 
by  erosion),  reaching  southward  in  long  arms  into  Salt  Wells  Valley. 

EL   PASO   RANGE. 

The  El  Paso  Range  is  a  rugged,  irregular  bunch  of  mountains  con- 
stituting an  outlier  of  the  southern  Sierra  Nevada,  south  of  the  Coso 
Range.  The  general  trend  of  its  ridges  is  east  and  west.  It  is 
bounded  on  the  north  by  Salt  Wells  Valley  and  on  the  south  by  the 
Mohave  Desert. 

SEDIMENTARY    ROCKS. 

According  to  Mr.  H.  W.  Fairbanks,^  the  stratified  rocks  of  a  meta- 
morphic  series  (probably  Paleozoic)  form  a  part  of  the  El  Paso  Range 
and  are  cut  by  the  granite. 


a  See  p.  204. 

i'Geol.  Surv.  California,  Vol.  I,  p.  474. 

c  Report  California  Miu.  Bureau,  1894.  p  474. 

dAm.  Geol.,  Vol.  XVII,  1890,  p.  145. 

eU.  S.  Geog.  Siarv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  124. 

/Am.  Geol.,  Vol.  XVII,  1896,  p.  73. 

fflbid.,  p.  65. 


SPURR.]  EL   PASO    RANGE.  215 

EARLY   TERTI ARIES. 

Mr.  Gilbert '^  lias  described  a  series  of  semiconsolidated  beds  in 
Redrock  Canyon,  in  the  southern  part  of  the  El  Paso  Monntains. 
These  beds  dip  westward  at  angles  ranging-  from  15°  to  30°  and  con- 
sist of  semiconsolidated  sand,  gravel,  and  volcanic  tnffs  interbedded 
with  basalts  and  rhyolites.  The  gravels  contain  pebbles  of  quartz 
and  various  volcanic  rocks. 

Mr.  H.  W.  Fairbanks^  describes  the  same  series  on  the  northern 
slope  of  the  El  Paso  Range,  where  it  also  consists  of  clays,  sandstone, 
volcanic  tuffs,  and  interbedded  lava  sheets.  The  whole  thickness  is 
estimated  to  be  1,000  feet  or  more,  and  the  series  extends  over  a  con- 
siderable area  between  the  El  Paso  Range  and  the  Sierra  Nevada. 
Between  clay  strata,  apparently  below  the  tuffs,  southeast  of  Black 
Mountain,  a  seam  of  coal  14  inches  thick  occurs  in  this  series.  In  the 
clay  above  the  coal  leaf  impressions  were  found,  which  Dr.  F.  H. 
Knowlton  considered  as  probably  belonging  to  the  Eocene.  Mr.  Fair- 
banks notes  that  andesite  appears  as  flows  between  the  beds  as  well 
as  in  dikes  cutting  them  and  as  sheets  capping  them. 

The  series  of  semiconsolidated,  tilted  tuffs,  sands,  gravels,  and  vol- 
canic sheets  is  evidently  identical  with  that  which  constitutes  the 
Funeral  Range  and  the  southern  end  of  the  Panamint  Range,  as 
described.  As  has  already  been  stated,  these  latter  beds  are  believed 
to  be  the  same  as  those  still  farther  north,  in  the  neighborhood  of 
Silver  Peak. 

IGNEOUS    ROCKS. 


Mr.  Gilbert^  notes  that  the  El  Paso  Mountains  have  a  core  of 
granite.     The  same  is  noted  by  Mr.  Fairbanks.'^ 

X  VOLCANIC   ROCKS. 

Mr.  Fairbanks*  notes  that  quartz-porphja-ies  appear  for  several 
miles  along  the  El  Paso  Range.  The  writer  found  that  near  Johan- 
nesburg and  Randsburg,  which  lie  among  low  hills  just  east  of  El 
Paso  Range,  the  jjrincipal  rock  is  an  ancient  sheared  rhyolite.  To 
one  looking  from  this  point  westward  this  same  rhyolite  appears  to 
form  a  considerable  portion  of  the  eastern  end  of  this  range  also.  It 
is  possible  that  this  is  the  same  rock  that  Mr.  Fairbanks  describes  as 
quartz-porphyry.  It  is  the  most  ancient  volcanic  rock  found  in  the 
region,  and  is  probably  nearly  contemporaneous  with  the  schistose 
volcanics  described  at  the   southern   end   of  the  Slate  Range.     It 

a\J.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  142. 
bNotes  on  the  Geology  of  Eastern  California:  Am.  Geol.,  Vol.  XVII,  1896,  p.  67. 
.      <-■  Op.  cit.,  p.  124. 

d  Am.  Geol.,  Vol.  XVII,  1896,  pp.  65,  152. 
t  Ibid.,  p.  152. 


216  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

underlies  the  early  Tertiar3^  sediments.  Mr.  Gilbert^'  notes  that  at 
the  eastern  end  of  the  El  Paso  Mountains  there  is  a  large  mountain 
of  acidic  lavas,  inclosing  and  nearly  concealing  a  core  of  granite. 

Mr.  Gilbert  also  notes  that  the  El  Paso  Mountains  are  flanked  to 
the  south  by  basaltic  and  trachytic  rocks.  Mr.  Fairbanks*  describes 
andesites  as  occurring  freely  in  this  range.  The  trachytes  described 
by  Mr.  Gilbert  are  probably  the  andesites  of  Mr.  Fairbanks,  since 
trachytes,  as  now  understood,  are  very  rare  in  this  region. 

STRUCTURE. 

Reasoning  from  the  tilting  of  the  earlj^  Tertiary  sediments,  Mr. 
Fairbanks  has  inferred  three  distinct  movements  of  Black  Mountain 
in  the  El  Paso  Range.  As  the  result  of  these  movements,  the  Ter- 
tiary beds  have  been  elevated,  tilted,  and  extensively  eroded. 

ORE   DEPOSITS. 

According  to  Mr.  Fairbanks,''  the  granite  of  the  El  Paso  Range  has 
been  in  different  places  mineralized,  and  contains  a  small  amount  of 
gold. 

THE  HILLS  FROM   RANDSBURG  EAST  TO  PILOT  KNOB. 

Forming  a  sort  of  continuation  of  the  El  Paso  Range  to  the  east  is 
a  series  of  low,  detached,  rounded,  or  level-topped  buttes,  connected 
by  low  ridges  or  Pleistocene  detrital  slopes,  or  entirelj^  separated  l\v 
an  undulating  detritus-covered  desert.  These  hills  have  a  general 
east-west  trend. 

SEDIMENTARY    ROCKS. 


On  the  north  slopes  of  Malapai  Mountain,  about  4  or  5  miles  north- 
east of  Johannesburg,  the  hornblende-pja'oxene-aleutite,  which 
makes  up  the  higher  portion  of  the  mountain,  is  underlain  by 
banded  or  bedded  rocks,  which  at  first  have  the  aspect  of  altered  vol- 
canies,  but  which,  when  examined  microscojjicallj^,  turn  out  to  be 
arkoses  of  different  degrees  of  coarseness.  Most  of  them  are  granitic, 
while  some  appear  to  be  in  part  derived  from  rhyolite.  These  arkoses 
probably  overlie  the  ancient  rhyolites.  They  are  firmly  consolidated, 
and  they  may  belong  to  the  series  of  Eocene  sediments  found  near 
here,  especially  in  the  El  Paso  Range  to  the  west,  and  on  the  east  in 
the  Leach  Point  Mountains. 

On  Pilot  Knob,  according  to  Mr.  Gilbert,'^  are  exposed  about  2,000 
feet  ^of  volcanic  products,  probabl}^  tuffs,  overlain  by  basaltic  lava. 
These  lie  upon  the  granite,  which  is  the  base  of  the  knob. 


nU.  S.  Geog.  Surv.  W.  One  Hundredth  Mer.,  Vol.  Ill,  p.  124. 
fi  Am.  Geol.,  Vol.  XVII,  1896,  p.  69. 
<•  Ibid.,  p.  153. 
dOp.  cit.,  p.  124. 


SPURR.]  HILLS    EAST    OF    RANDSBURG.  217 

IGNEOUS   ROCKS. 

The  lower  portion  of  Pilot  Knob  is  of  siliceous  biotite-granite.  To 
the  south,  southeast,  and  west  this  same  body  of  granite  extends 
for  miles.  Many  of  the  numerous  small  hills,  which  emerge  from 
the  general  plateau  level  of  the  desert  area  of  granite,  are  often 
capped  l\y  patches  of  basic  lava  or  stratified  Tertiary  sediments. 

All  the  hills  in  the  vicinity  of  Randsburg  and  Johannesburg  con- 
sist of  ancient  sheared  rhyolites,  often  considerably  decomposed. 
When  fresh,  the  rock  appears  to  be  a  biotite-rhyolite,  but  as  often  as 
not  the  biotite  has  completelj^  disappeared  on  account  of  decomposi- 
tion, and  the  other  minerals,  notably  orthoclase,  have  also  become 
considerably  altered.  It  is  in  this  rock  that  the  gold-bearing  veins  of 
the  district  occur,  and  the  rhj^olite  has  been  locally  altered  at  the  time 
of  the  introduction  of  the  ores  so  as  to  become  a  semijasperoid,  and 
sometimes  even  passes  into  vein  quartz  by  a  process  which  appears  to 
be  chiefly  replacement. 

This  ancient  sheared  rhyolite  resembles  the  sheared  volcanics  of 
the  southern  end  of  the  Slate  Range. 

The  greater  portion  of  Malapai  Mountain  is  made  up  of  a  consider- 
able thickiiess  of  lava,  which  overlies  the  rhj^olite  and  underlies 
basalt.  Its  intermediate  age  is  also  at  once  evident  from  its  appear- 
ance. A  number  of  specimens  of  this  rock  have  been  studied  and 
show  it  to  be  probably  a  hornblende-i^yroxene-biotite-aleutite.  This 
rock  has  no  ai)parent  banding,  and  has  a  great  variet}^  of  texture 
exposed  by  the  erosion  which  it  has  undergone. 

The  basaltic  rock  which  caps  Pilot  Knob  was  also  encountered  just 
west  of  this  mountain.  The  sj)ecimen  taken  here  proves  to  be  a 
P3^roxene-basalt,  evidently  belonging  to  the  same  general  series  as  the 
olivine-basalt  of  the  region.  In  the  Browns  Peak  region,  in  the  south- 
ern end  of  the  Panamint  Range,  the  same  basalt  occurs  in  a  number 
of  buttes,  caj)ping  other  rocks. 

At  Johannesburg  a  dike  of  pyroxene-olivine-diabase-porjjhyry  was 
found,  cutting  the  ancient  rhyolites.  This  dike  is  probably  to  be  cor- 
related with  the  basaltic  flows. 

The  succession  of  igneous  rocks  in  this  district,  therefore,  is,  so  far 
as  made  out,  biotite-granite,  biotite-rhyolite,  hornblende-pyroxene- 
biotite-aleutite,  pyroxene-basalt,  and  pyroxene-olivine-diabase-por- 
Pbyry.  ^ 

ORE   DEPOSITS. 

Gold-bearing  veins  are  very  numerous  in  the  ancient  rhyolite  in  the 
vicinity  of  Johannesburg  and  Randsburg.  The  veins  generally  con- 
sist of  a  central  thin  seam  of  quartz,  flanked  above  and  below  by 
sheared,  silicified,  and  discolored  country  rock,  which  also  may  carry 
quartz  nodules  or  segregations.  There  are  also  larger  veins  of  clearer 
bluish  quartz.     Certain  portions  of  these  quartz  veins  and  altered 


218  GEOLOGY    OF    NEVADA  SOUTH    OF   40TH   PARALLEL,     [bull  208. 

sheared  zones  carry  free  gold  in  such  quantities  as  to  malve  them  high- 
grade  ores.  The  schistosity  of  the  rocks  has  a  general  northeast  dip 
of  15°  and  20°,  and  the  veins  are  usually  conformable  to  this. 

SIERRA   NEVADA. 

Properly  speaking,  the  Sierra  Nevada  does  not  constitute  part  of 
the  present  study.  It  was  thought  best,  however,  to  include  the  east- 
ern edge  of  this  important  mountain  chain  so  as  to  show  its  relations 
to  the  region  lying  east  of  it.  For  the  sake  of  uniformity  a  few  brief 
descriptive  notes  will  be  given.  The  region  is,  geologically,  a  compli- 
cated one,  but  has  been  the  subject  of  a  great  amount  of  careful 
study  by  many  geologists,  while  the  Basin  region  has  been  left  almost 
untouched. 

As  a  topographic  feature  the  Sierra  Nevada  is  a  broad  range,  attain- 
ing considerable  elevation  and  having  many  well-defined  peaks.  Its 
eastern  face  constitutes  a  sharp  western  limit  to  the  interior  Basin 
region,  which  is  characterized  by  narrow  ridges  of  generall}^  less, 
height,  with  flat  desert  valleys  between.  Unlike  the  Basin  ranges,' 
the  Sierra  Nevada  is  well  watered  and  wooded,  and  from  this  circum- 
stance has  derived  a  different  minor  topograph}^  from  that  of  the 
Basin  ranges. 

SEDIMENTARY   ROCKS. 

Mr.  Turner «  states  that  it  is  probable  that  there  are  in  the  Sierra 
Nevada  formations  ranging  in  age  from  Archean  or  Algonkian  to 
Recent.  The  rocks  have  been  strongly  affected  by  compression  of 
the  crust,  which  has  produced  close  folding  and  schistosity,  and  has 
frequently  obliterated  the  original  nature  and  age  of  the  sediments. 
In  different  parts  of  the  range, ^  however,  the  great  series  of  auriferous 
slates  has  been  found  to  contain  Silurian,  Carboniferous,  Triassic,  and 
Jurassic  fossils.  The  superjacent  series  of  less  altered  rocks  consists 
of  strata  ranging  from  the  Upper  Cretaceous  through  the  Tertiary. 
Large  portions  of  the  range  are  covered  with  auriferous  river  gravels 
of  Neocene  age. 

Within  the  area  represented  by  the  map  accompanying  this  bulle- 
tin the  stratified  rocks  occupy  onlj^  restricted  areas,  surrounded  by 
great  masses  of  granite. 

CAMBRIAN. 

Just  west  of  Mono  Lake  there  is  a  considerable  patch  of  quartzites 
and  schists,  mapped  by  Mr.  Turner '^  as  Paleozoic.  Mr.  Walcott^'  sub- 
sequently visited  these  rocks,  and  considers  them  identical  with  the 
Cambrian  series  of  the  White  Mountains.     Southward  from  here  a 

"Seventeenth  Ann.  Eept.  U.  S.  Geol.  Survey,  Pt.  I,  p.  531. 

bK.  W.  Turner:  Fourteenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  II,  p.  445. 

I- Seventeenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  PI.  XVIII. 

d Personal  commvinication  to  the  writer. 


SPURR.]  ,  SIERRA    NEVADA.  219 

short  distance,  on  the  Nortli  Fork  of  San  Joaqnin  Biver,  is  an  area  of 
similar  rocks,  according  to  Mr.  Turner.  Still  farther  southeast,  not 
far  from  Big  Pine,  in  Owens  Valley,  Mr.  Walcott  found  small  patches 
of  Cambrian,  and  considers  that  these  separate  occurrences  may 
belong  to  a  single  belt. 

CARBONIFEROUS. 

On  the  extreme  western  edge  of  the  map,  northeast  from  Mariposa, 
is  an  area  of  Carboniferous  rocks  which  has  been  studied  by  Mr. 
Turner. 

TRIASSIC. 

Northwest  of  Owens  Lake,  on  the  eastern  flanks  of  the  Sierra 
Nevada,  is  an  area  of  Triassic  beds,  consisting  mainly  of  ancient 
lavas  and  tuffs,  similar  to  the  Triassic  rocks  of  the  White  Mountains 
on  the  other  side  of  the  valley. 

Some  distance  south  of  here  the  region  around  Owens  Peak  con- 
sists of  rocks  similar  to  the  Triassic  formations  just  described.  No 
fossils  were  found  in  this  region. 

Just  east  of  Silver  City,  which  is  southeast  of  Lake  Tahoe,  Mr. 
Turner  has  mapped  several  small  exposures  of  sedimentary  rock. 
In  his  reconnaissance  map"  these  areas  are  mapped  as  doubtful 
Juratrias. 

JURASSIC. 

A  long  tongue  of  the  Jurassic  rocks  which  occur  at  Mariposa  comes 
into  the  map  at  its  extreme  w^estern  end. 

IGNEOUS   KOCKS. 

The  Sierra  Nevada  contains  enormous  quantities  of  igneous  rocks, 
both  coarse  and  fine  grained,  and  both  surface  flows  and  plutonic 
and  dike  masses.  According  to  Mr.  Turner,^  the  coarse-grained 
rocks  consist  mosth^of  granite  and  grauodiorite,  wdth  diorite,  gabbro, 
etc.,  while  the  abundant  Tertiary  lavas  consist  of  andesite,  rhyolite, 
and  basalt. 

In  the  area  covered  by  the  map  accompanying  this  bulletin  (PI.  I) 
the  greater  part  of  the  Sierras  consist  of  coarse,  granular,  igneous 
rocks,  among  which  granite  and  granitic  rocks  occupy  the  chief  place. 

Overlying  the  ancient  granites,  within  the  limit  of  this  map,  come 
occasional  areas  of  Tertiary  lavas.  Mr.  Turner  has  kindly  supplied 
the  writer  with  notes  concerning  two  of  these  regions,  one  of  which  is 
in  the  neighborhood  of  Silver  City  and  the  other  at  the  extreme 
southern  end  of  the  range^  just  north  of  the  cut  of  the  Southern 
Paciflc  Railway,  between  Tehachapi  and  Mojave.  At  the  first-named 
locality  Mr.  Turner  obser  <^ed  at  one  point  a  thickness  of  half  a  mile  of 

a  Seventeenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  PI.  XVIII. 
6Fourteenth  Ann.  Kept.  U.  S.  Geol.  Survey,  Pt.  II,  p.  470. 


220  GEOLOGY    OF    NEVADA  SOUTH    OF    40TH    PARALLEL,     [bull.208. 

volcanic  lavas  and  tuffs.  The  lavas  occupy  several  separated  areas, 
and  in  them  occur  the  ore  deposits  of  the  region.  In  the  second 
locality  Tertiary  lavas  with  Tertiary  sediments  make  up  the  southern 
flanks  of  the  range. 

On  the  flanks  of  the  range,  about  Fish  Springs,  are  flows  of  basalt, 
described  by  Mr.  W.  A.  Goodyear."  Mr,  H.  W.  Fairbanks^  suggests 
that  these  ma}^  be  of  the  same  age  as  the  basalts  of  the  Coso  Range. 
According  to  Mr.  Fairbanks,  also,  "andesite  covers  a  great  stretch  of 
country  about  the  head  of  Owens  River,  forming  the  crest  of  the 
Sierra  Nevada  between  it  and  the  head  of  the  North  Fork  of  the  San 
Joaquin  River." 

STRUCTURE. 

It  has  been  recognized,  from  the  evidence  which  the  Mesozoic  strata 
of  the  Sierra  Nevada  offer,  that  the  folding  of  the  range  was  initiated 
at  the  close  of  Jurassic  time,  after  the  Mariposa  beds  were  deposited. '^ 
During  the  period  which  succeeded  this  Jurassic  movement  erosion 
produced  great  changes,  and  gradually  brought  about  the  formation 
of  a  topograjjliy  of  little  relief,  the  mountains  being  low,  the  valleys 
broad,  and  the  streams  sluggish.  This  period  appears  to  have  reached 
its  maximum  during  the  Miocene.  ^^  Subsequent  to  the  development 
of  this  style  of  topography  there  was  a  general  disturbance  which 
brought  about  the  acceleration  of  the  streams  and  the  cutting  of  deep 
valleys,  leaving  high  ridges  between.  This  disturbance  apparently 
consisted  in  part  of  differential  movement,  but  there  are  evidences  that 
the  whole  mass  of  the  Sierra  was  uplifted  at  least  4,000  feet,  and  possi- 
bly as  much  as  7,000  feet.*  Mr.  Turner^  concludes,  from  the  fact 
that  the  Neocene  Gulf  deposits,  at  the  very  west  edge  of  the  range, 
have  been  elevated  at  least  1,000  feet  above  their  original  position, 
that  the  mountains  were  uplifted  as  a  whole,  and  not  by  a  tilt  to  the 
westward,  for  in  the  latter  case  the  west  edge  of  the  block  so  tilted 
would  remain  approximately  at  its  original  elevation. 

During  the  latter  ]3art  of  the  time  that  the  Sierra  Nevada  region 
was  being  worn  down,  a  great  series  of  auriferous  gravels  was  depos- 
ited by  the  sluggish  streams.  These  gravels,  after  the  uplift  and  the 
acceleration  of  the  drainage,  remained  often  in  the  highest  parts  of 
the  range  and  in  the  regions  between  the  present  river  valleys,  especi- 
ally where  protected  by  later  cappings  of  lava. 

The  eastern  face  of  the  Sierra,  for  a  distance  of  several  hundred 
miles,  is  very  steep,  contrasting  strongly  with  the  comparatively 
uniform  and  gentle  slope  on  the  west.  The  earliest  observ^ers  saw  in 
this  a  probable  fault  scarp.     Mr.  Clarence  King  ^  was  one  of  the  first 

a  Kept,  of  Cal.  State  Mining  Bureau,  Vol.  VIII,  pp.  271-373. 

&Am.  Geol.,  Vol.  XVII,  p.  73. 

cH.  W.  Turner,  Seventeenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  p.  532. 

rf  J.  S.  Diller,  Fourteenth  Ann.  Rept.  U.  S.  Geol.  Survey.  Pt.  II,  p.  421. 

^Ibid.,  p.  433. 

/Fourteenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  II,  p.  443. 

ffU.  S.  Geol.  Expl.  Fortieth  Par.,  Vol.  I,  p.  744. 


SPURR]  SIERRA    NEVADA.  221 

of  these,  and  the  hj^pothesis  has  been  accepted  by  nearly  all  succeed- 
ing geologists. 

The  observations  most  in  favor  of  the  existence  of  a  fault  are  those 
of  high  gravels  on  the  very  summits  of  the  mountains  above  the  steep 
eastern  scarp.  Mr.  Diller'*  has  noted,  at  the  northern  end  of  the 
range,  that  these  gravels  are  displaced  by  a  fault  having  about  3,000 
feet  vertical  displacement,  which  extends  along  the  eastern  face  of  the 
range.  Mv.  Russell  ^  also  found  water- worn  gravels  on  the  top  of  the 
range  to  the  west  of  Mono  Lake,  at  an  altitude  of  about  11,500  feet. 
Mr.  Turner '■  found  well-rounded  pebbles  on  the  main  summit  of  the 
range  a  few  miles  northwest  of  Tower  Peak,  at  an  elevation  of  over 
9,000  feet.  Mr.  Turner  observes  that  these  gravel  patches  along  the 
crest  of  the  range  undoubtedly  represent  remnants  of  Neocene  river 
beds,  now  almost  entirely  eroded. 

The  writer  does  not  know  of  any  case  where  actual  faulting  has 
been  proved  by  displacement  of  rocks,  unless  it  is  the  case  of  the  dis- 
placement of  i-ecent  lavas  along  the  crest  north  of  Honey  Lal^e, 
described  by  Mr.  Diller.'^  Even  in  many  of  the  instances  Avhere  river 
gravels  have  been  found  at  the  summit  of  the  range,  it  is  j^ossible 
that  some  other  hypothesis  maybe  found  to  explain  their  presence,  as 
well  as  that  of  faulting.  Along  most  of  the  range  the  rocks  of  the 
Sierra  Nevada  scarp  do  not  stop  abruptly,  but  are  found  in  the  ranges 
lying  next  east.  The  eastern  face  of  the  range  is  not  the  boundary 
between  the  granites  on  the  west  and  the  volcanics  on  the  east, 
as  supposed  by  Russell.^  In  the  White  Mountain,  Pine  Nut,  and 
other  ranges  Ijang  next  east  of  the  Sierra,  granitic  rocks  are  found 
forming  the  core,  and  also  in  some  of  the  ranges  farther  east, 
growing,  however,  continually  lower  until  no  longer  exposed  by 
erosion. 

Mr.  King/  considered  that  the  fault  along  the  eastern  scarj)  was 
formed  either  within  the  Eocene  or  at  the  close  of  Eocene  time,  since 
it  evidentl}^  existed  before  the  formation  of  the  Miocene  Piute 
Lake,  which  was  an  inclosed  inland  body  of  water  and  was  shut 
off  from  the  sea  by  the  barrier  of  the  Sierra.  On  the  other  hand, 
Mr.  Diners'  considered  that  the  fault  along  the  eastern  scarp  must 
have  been  formed  very  recently,  in  Jjost-Tertiary  time,  ^ince  the  Ter- 
tiary river  gravels  and  most  of  the  volcanics  are  displaced.  South 
from  the  area  observed  by  Mr.  Diller,  however,  Mr.  Lindgren^*  found 
that  the  eastern  slope  of  the  range  was  formed  before  the  eruption 
of  the  andesitic  lavas. 

"Fourteenth  Ann.  Rapt.  U.  S.  Geol.  Survey,  Pt.  II,  p.  4:e. 

(- Eighth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  p.  322. 

f  Fourteenth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  II,  p.  442. 

d  Eighth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  p.  429. 

<? Eighth  Ann.  Rept.  U.  S.  Geol.  Survey,  Pt.  I,  p.  371, 

/  U.  S.  Geol.  Expl.  Fortieth  Par.,  Vol  I,  p.  744. 

3  Fourteenth  Ann.  Rept.  U.  S.Geol.  Survey,  Pt.  II,  p.  432. 

/iBull.  Geol.  See.  Am.,  Vol.  IV,  pp.  257  398. 


222  GEOLOGY    OF    NEVADA   SOUTH    OF    40TH    PARALLEL,     [bull. 208. 

Since  writing  the  above  the  writer  has  obtained  tlie  following  addi- 
tional information : 

On  the  east  front  of  the  Sierra,  between  Carson  and  Markleeville, 
Mr.  Lindgren  has  found  evidence  of  recent  faulting  along  the  base  of 
the  mountains.  Near  Genoa,  Pleistocene  alluvial  deposits  are  dis- 
placed some  40  feet  by  this  fault.  Another  point  is  the  behavior  of 
the  Carson  River,  which,  on  emerging  from  the  mountains,  increases 
its  grade  abruptly,  suggesting  comparatively  recent  dislocation  of  its 
valley.  Mr.  Lindgren  believes  that  the  first  dislocation  along  the 
eastern  face  of  the  Sierra  Nevada  took  place  at  the  close  of  the  Creta- 
ceous and  that  movement  has  continued  at  intervals  down  to  the 
present  day.  The  faulting  was  not  simple,  but  complex.  A  number 
of  more  or  less  parallel  faults  may  be  distinguished  within  a  belt  25 
miles  wide.^' 


a  Auriferous  gravels  of  the  Sierra  Nevada:  Jovir.  Geol.,  Vol.  IV,  No.  8,  and  oral  communica- 
tion to  the  writer. 


INDEX. 


Page. 

Algonkian  rocks  in  Sierra  Nevada 218 

Alhambra  Hills,  geologic  structure  of SO 

Allepaw  Canyon,  geologic  structure  of 67 

Alps,  Austrian,  resemblance  of  certain  fos- 
sils to  those  of 22 

Altoona  Pass,  geology  of 89 

Amargosa  Range,  sjTionyra 187 

Amargosa  Valley,  Cal.,  geology  of 191, 194-195 

Antelope  Range,  geology  of 37-38 

Antimony,  Belmont  region  . . .  .• 93 

Panamint  Range,  Cal 205 

Toyabe  Range 97 

Applegartli  Canyon,  geologic  structure  of..        07 

Archean  rocks,  in  Colorado  Canyon 133, 134 

Colorado  Range 139 

Deep  Creek 26 

Egan  Range 47 

Eldorado  Range 139 

Humboldt  Range 60 

Kprn  Mountains 26 

Sierra  Nevada 218 

Snake  Range 26 

Virgin  Range 131-132 

Area  mapped 16 

Argus  Range,  Cal.,  geology  of 212 

Arrow  Canyon  Range,  geology  of 154 

Arsenic  in  Panamint  Range,  Cal 205 

Aubrey  formation,  described '. . . . .        18 

occurrence  of 131,133,135,172 

Austin,  ores  in  region  of 97 

Bald  Mountain,  geologic  structure  of 65 

situation  of 77 

Beaver  Dam  Wash,  geologj'  of  region 131 

Belmont,  geology  of  region 90-93 

Belted  Range,  geology  of 163-164 

Big  Pine,  Cal.,  geology  of 207 

Bird  Spring  ^Mountains,  geology  of 179 

Black  Mountains,  synonym 187 

Bonneville,    Lake    (Pleistocene),    referred 

to 34,35 

Borax,  in  G^ape^^ne  Range,  Cal 190 

Boulder  Canyon,  geology  of 134 

situation  of 136, 137 

Bristol,  geology  of 46 

Bro^vns  Peak,  Cal. ,  geology  of 204 

Biirnt  Rock  Mountains,  Cal.,  geology  of .  205-200 
Cambrian  rocks,  in  Candelaria  Mountains.      113 

Colorado  Canyon 133 

Diamond  Range 83 

Egan  Range 47-48 

Gold  Mountain,  Cal 188 

Grapevine  Range,  Cal 201 

Highland  Range 41,140 


Cambrian  rocks,  in  Humboldt  Range 60 

Kern  Mountains 26-30 

Kingston  Range,  Cal 196-197, 200 

Las  Vegas  Range 155 

Lone  Mountain 184 

Meadow  Valley  Range 149 

Panamint  Range,  Cal 201, 202 

Piiion  Range S8 

Quinn  Canyon  Range 69 

Schell  Creek  Range 38-42 

Silver  Peak  Range 184 

Snake  Range 26-30 

Sierra  Nevada 218 

Spring  Mountain  Range 165-166 

Timpahute  Range 159 

Toyabe  Range 94-95 

White  Mountain  Range,  Cal 207 

White  Pine  Range 61 

Candelaria  Mountains,  geology  of 113-114 

Carboniferous    rocks,    in    Arrow    Canyon 

Range 154 

Candelaria  Mountains 113 

Clarks  Peak  Mountains,  Cal 200 

Colorado  Canyon 133 

Diamond  Range 81-83 

Egan  Range 49, 51-52 

Funeral  Range,  Cal 188, 189 

Grant  Range 72 

Grapevine  Range,  Cal 188, 189 

Humboldt  Range 60 

Las  Vegas  Range 156-157 

Long  Valley  RJinge 55--56 

Meadow  Valley  Range 140, 149-150 

Mormon  Range 134-135, 140 

Muddy  Range 137 

Pahranagat  Range 153 

Panamint  Range,  Cal 202 

Pancake  Range 77-78 

Piiion  Range 88 

Schell  Creek  Range 39, 40, 43-44 

Sierra  Nevada 218, 219 

Snake  Range 31-34 

south  of  Spring  Mountain 180, 181 

Spring  Mountain  Range 165-173 

Toyabe  Range 94, 95 

Virgin  Range 131-132 

W  hite  Mountain  Range,  Cal 208 

White  Pine  Range 63-65 

See  also  Mississippian;  Paleozoic. 

Carson,  geology  of  region 124 

Carson  River,  geology  of  valley  of 121 

Cedar  Range,  geologj^  of 36-37 

Charleston  Peak  and  Canyon,  geology  of  . .      167 

223 


224 


INDEX. 


Page. 

Cherry  Creek,  dikes  near 53 

geology  of 49 

geologic  structure  near 74 

Chihuahua  Canyon,  geology  of 82 

Chokup  Pass,  geology  of 82-84 

Chuar  formation,  described 18, 19 

occurrence  of 133 

Olarks  Peak  Mountains,  Cal.,  geology  of..'.      200 

Cloverdale,  topography  of 94 

Clover  Valley  Mountains,  geology  of 36-37 

Coal  Burners  Mountain,  geologic  structure 

of 65 

situation  of 77 

Coal,  El  Paso  Range,  Cal 215 

impure,  in  Pancake  Range 81 

Muddy  Creek 137 

Colorado  Plateau,  geology  ot 172, 173 

Colorado  Range,  geology  of 138-139 

Colorado  River,  geology  of  canyon  and  val- 
ley    131-134 

Comstock  lode,  situation  of 129 

Copper,  Austin  region 97 

Belmont  region 93 

Ellsworth  region 103 

Excelsior  Range 113 

Mineral  City 54 

Opal  or  Clarks  Peak  Mountains,  Cal 200 

Panamint  Range,  Cal 205 

Coso  Range,  Cal.,  geology  of 214 

Cottonwood  Spring,  geology  of 168, 

170, 173, 177, 178 
Cretaceous.    See  also  Mesozoic. 
Cretaceous,  Upper,  rocks  in  Sierra  Nevada.      218 

Dalzell  Canyon,  geology  of 118, 119, 126 

Darwin  Range,  Cal.,  geology  of 212 

Dayton,  geology  of  region 120-124 

Death  Valley,  topography  and  geology  of. .     187, 
190,191,193,194,201-203 

Deep  Creek  Mountains,  geology  of 29 

Deep  Creek  Valley,  geology  of 34 

Delamar,  geology  of  region 149 

Desert  Creek,  geologj^  of  region 127, 128 

Desert  Mountains,  geology  of 106 

Desert  Range,  geolo,gy  of 160-161 

Desatoya  Range,  geology  of 102 

Devonian  rocks,  in  Antelope  Range 37 

Clarks  Peak  Mountains,  Cal 200 

Colorado  Canyon 133 

Desert  Range 161 

Diamond  Range 82 

Egan  Range 49-51 

Funeral  Range,  Cal 188 

Golden  Gate  Range 58 

Grant  Range 71-72 

Grapevine  Range,  Cal 188 

Hiko  Range 152 

Humboldt  Range 60 

Kingston  Range,  Cal 197-198 

Las  Vegas  Range 156 

Long  Valley  Range 56 

Pahranagat  Range 153 

Pahroc  Range 162 

Pancake  Range 78 

Piiion  Range 88 

Quinn  Canyon  Range 71-72 

Schell  Creek  Range 41, 43 


Page. 

Devonian  rocks,  in  Toyabe  Range 95 

Wahweah  Range 90 

White  Pine  Range 63 

See  also  Paleozoic. 

Diamond  Peak,  geologic  structure  of 83 

Diamond  Peak  quartzite,  described 18 

Diamond  Range,  geology  of 81-84 

Dikes.    See  also  Igneous  rocks. 

Dikes,  in  Egan  Range 53 

Ellsworth  Range 102 

Highland  Range 44 

Schell  Creek  Range 35 

Snake  Range 35 

Toquima  Range 92 

Dome,  The,  geologic  structure  of 97 

Downieville,  geology  of  region 100, 102, 103 

Dutton,  C.E.,  cited 131 

Egan  Range,  geology  of 47-54 

Eldorado  Canyon,  geology  of 121, 123 

Eldorad  o  Range,  geology  of 139 

Ellsworth  Range,  geology  of 99-103 

El  Paso  Range,  Cal., geology  of 214-216 

Ely,  topography  of 47 

Ely  Range,  geology  of 42 

Emmons,  S.  F.,  cited 101 

Eocenerocks,  inBurntRockMountains,Cal.      206 

Excelsior  Range Ill 

Leach  Point  Mountains,  Cal 206 

See  also  Tertiary. 

Esmeralda  formation,  described 19 

occurrence  of 106,  111,  112, 114, 199, 202 

Eureka,  geology  of  district 84 

Eureka  quartzite,  described 19 

occurrence  of 31, 32, 49, 86, 202 

Excelsior  Flat,  geology  of 110 

Excelsior  Range,  geology  of 109-113 

Faulting.    .S'fe  Structure,  geologic. 

Fault,  scissors,  defined 1.53 

Folding.    See  Structure,  geologic. 

Fossil  Butte,  geology  of 1-52 

Fossils,    Cambrian,    of     White     Mountain 

Range,  great  age  of 207 

Fossils,  Cambrian,  list  of,  Egan  Range 48 

list  of,  Snake  Range 31 

occurrence  of,  Desert  Range 161 

Grapevine  Range,  Cal 201 

Kingston  Range,  Cal 197 

Las  Vegas  Range 155, 156 

Schell  Creek  Range 39, 41, 42 

Silver  Peak  Range 184, 185 

Spring  Mountain  Range 165 

Timpahute  Range 159 

White  Mountain  Range,  Cal 207 

Fossils,  Carboniferous,  list  of.  Grant  Range.        72 
list  of,  Humboldt  Range,  near  Fremont 

Pass 60 

Schell  Creek  Range 44-45 

White  Mountain  Range,  Cal 208 

occurrence  of,  Candelaria  Mountains. . .      114 

Cottonwood  Canyon,  Cal 202 

Desert  Range 161 

Highland  Range 45 

Las  Vegas  Range 157 

Schell  Creek  Range '       39 

Snake  Range 28,29 

Toyabe  Range 94, 95 


INDEX. 


225 


Page. 
Fossils,  Carboniferous,  Lower,  list  of,  Egau 

Range 51 

list  of.  Spring  Mouiatain  Range. . .  166-1()9, 172 

occurrence  of,  Las  Vegas  Range 157 

Fossils,  Carboniferous,  Upper,  list  of.  Dia- 
mond Range S2 

list  of,  Egan  Range 51 

Long  Valley  Range 55-56 

Meadow  Valley  Canyon l34 

Meadow  Valley  Range 149, 150 

Pancake  Range 78 

Snake  Range '. 32, 33 

south  of  Spring  Mountain ISd 

White  Pine  Range 63-64 

occurrence  of.  Las  Vegas  Range 156, 157 

Pleasant  Valley  (near) 33 

Snake  Range 29,32,33 

Spring  Mountain  Range 167, 170-172 

Fossils,  Cretaceous,  Excelsior  Range 109 

Fossils,  Devonian,  list  of,  Diamond  Range. .        83 

list  of,  Egan  Range 50 

Golden  Gate  Range 58 

Highland  Range 43 

Kingston  Range,  Cal 197 

occurrence  of.  Desert  Range 161 

Las  Vegas  Range 156 

Pyramid  Peak,  Cal 188 

Quinn    Canyon     Range,  or    Grant 

Range 71 

Fossils,  Eocene,  occurrence  of,  El  Paso  Range, 

Cal 215 

occurrence  of,  Monte  Cristo  Motm tains .      106 
Fossils,  fresh  water,  occurrence  of,  Monte 

Cristo  Mountains 105-106 

Fossils,    Jurassic,    occurrence    of.  Muddy 

Creek 137 

occurrence  of.  Spring  Mountain  Range.      173 
Fossils.    Miocene,    occurrence    of,    Monte 

Cristo  Mountains 106 

Fossils,   Ordovician,   list  of.   Golden    Gate 

Range ". 58 

list  of,  Grant  Range 71 

Hot  Creek 85 

Humboldt  Range 61 

Quinn  Canyon  Range 70-71 

Schell  Creek  Range 42, 43 

Snake  Range 30, 31,  33 

occurrence  of,  Antelope  Range 37 

Desert  Range 160, 161 

Las  Vegas  Range 156 

Snake  Range 33 

Tjbo 86 

White  Pine  Range,  near  Hamilton .        63 
Fossils,   Permian,   list    of,   Harnels    Peak, 

Egan  Range .52 

occurrence  of.  Spring  Mountain  Range.     171, 

172, 174 
Fossils, Silurian.  Seealso Fossils.Ordovician. 
Fossils,  Silurian,  list  of.  Hot  Creek  Range. .        86 
list  of,  Quinn  Canyon  Range  and  Grant 

Range 71 

occurrence  of,  Fossil  Butte 1.52 

Grapevine  Pea  k,  Cal 188 

Pahranagat  Range 153 

Panamint  Range,  Cal 202 

Toyabe  Range 94, 95 

Bull.  208—03 15 


Page. 
Fossils,    Silurian,    occtirrence    of,    White 

Mountain  Range,  Cal 208 

Fossils,  Tertiary,  occurrence  of.  Excelsior 

Range 109 

occurrence  of,  Monte  Cristo  Mountains.      106 
Fossils,  Triassic,  occurrence  of.  Good  Spring .      1 74 
occurrence  of.  White  jMountain  Range, 

Cal 208, 209 

Pine  Nut  Range 123 

Funeral  Range,  Cal.,  geology  of 187-194 

Gabbs  Valley  Range,  geology  of 107-109 

Geologic  section.    See  Section,  geologic. 
Geologic  structure.    .Sfe  Structure,  geologic. 

Gold,  Cherry  Creek 54 

Darwin  or  Argus  Range,  Cal 213 

El  Paso  Range,  Cal 216 

Johannesburg  and  Randsburg  region, 

Cal 217-218 

Keystone  Mine 174 

Mineral  City,  Nev 54 

Osceola,  Nev 36 

Postoffice  Springs,  Cal 205 

Sierra  Nevada  region 220 

Silver  Peak  Range 186 

Spring  Mountain  Range 174 

White  Mountain  Range,  Cal 211 

Golden  Gate  Range,  geology  of 57-59,  74, 75 

Gold  Mountain,  Cal,,  geology  of 187 

Good  Spring,  geology  of 171, 174, 178, 179 

Grand  Canyon  of   the  Colorado,  geology 

of  133-134, 172, 173 

Grand  Canyon  group,  described- . : 18, 19 

Grand  Wash,  geology  of 131, 132 

Grant  Range,  geology  of 68-76 

sketch  sections  of 74, 75 

Grapevine  Range,  Cal.,  geology  of...  187-194,201 

Hackberry  Canyon,  geology  of 141, 144, 147 

Hamburg  limestone  and  shale,  described. .        19 

occurrence  of 63 

Hamels  Peak,  fossils  from 52 

Hamilton,  ores  in  region  of 68 

Hawthorne,  geology  of  region 115 

Highland  Range,  geology  of 38-47 

Hiko  Range,  geological  structure  of 75 

geology  of 152-153 

Hot  Creek  Canyon,  geology  of 87 

Hot  Creek  Range,  geology  of 84-88 

Humboldt  formation,  described 19 

occurrence  of 78 

Humboldt  Range,  geology  of 59-61 

Igneous  rocks,  in  Antelope  Range 37-38 

Burnt  Rock  Mountains. : 206 

Candelaria  Mountains 114 

Coso  Range,  Cal 214 

Darwin  or  Argus  Itange,  Cal 212 

Desert  Mountains 106 

Diamond  Range 83-84 

Egan  Range 52-.53 

Ellsworth  Range 102 

El  Paso  Range,  Cal 215 

E.xcelsior  Range 112 

Funeral  Range 192 

Gabbs  Valley .' 108 

Golden  Gate  Range 5S 

Grant  Range 73 

Grapevine  Range,  Cal 192 


226 


INDEX. 


Igneous  rocks,  in  Hiko  Range 152 

Hot  Creek  Range 87  ; 

Humboldt  Range 61 

Kawich  Range 181 

Kingston  Range,  Cal 199 

Leach  Point  Mountains,  Cal 206 

Lone  Mountain 184 

Long  Vallej'  Range 56 

Meadow  Valley  Canyon 141, 147 

Meadow  Valley  Range 150 

Monte  Cristo  Mountains 106 

Monitor  Range 89 

Mormon  Range 135 

Muddy  Range 137, 138 

Pahranagat  Range 154 

Pahroc  Range ; .      151 

Panamint  Range,  Cal 201-204 

Pancake  Range 79 

Pilot  Mountains 105 

Pilot  Knob  to  Randsburg,  Cal 217 

Pine  Nut  Range 120-122 

Pinon  Range 88 

Quinn  Canyon  Range 72-73 

Ralston  Desert 182-183 

Reese  River  Range 99 

Reveille  Range 163 

Schell  Creek  Range 44 

Sierra  Nevada    219 

Silver  Peak  Range 186 

Slate  Range,  Cal 213-214 

Smith  Valley  Range 118 

Snake  Range 35 

Spring  Mountain  Range 174-175 

Sweetwater  Range 126-128 

Timpahute  Range 159 

Toquima  Range 92 

Toyabe  Range 95-96 

Virgin  Range 131, 132 

Virginia  Range 129-130 

Wahweah  Range 90 

White  Mountain  Range,  Cal 208, 210-211 

Walker  River  Range 115-116 

White  Pine  Range 65 

Worthington  Mountains 76 

Indian  Spring,  geology  of  region 165-167,  ISO 

tone,  geology  of  region 99 

Iron,  Austin  region 97 

Belmont  region 93 

Jeff  Davis  Peak.    See  Wheeler  Peak. 

Jurassic  rocks,  in  Pilot  Mountains 104 

Sierra  Nevada 218, 219 

Spring  Mountain  Range 169-171, 173, 174 

See  also  Mesozoic. 

Kawich  Range,  geology  of 181 

Kern  Mountains,  geology  of 26,  29, 35,  36 

topographic  situation  of 25 

King,  Clarence,  cited 101 

Kingston  Range,  Cal. ,  geology  of 195-200 

Koipato  formation,  described 19 

occurrence  of  101, 209 

Lake  Bonneville  ( Pleistocene ) 34, 35 

Lake  Lahontan  ( Pleistocene) ,  traces  of 116- 

117, 124 

Lake  Mono,  former  height  of 210 

Lake  Shoshone   (Pliocene),  sediments   of, 

in  Soda  Springs  Valley 104 

sediments  of,  in  Silver  Peak  Range 186 


Lake  Shoshone  (Pliocene),  sedimentsof,  in 

White  Mountain  Range 209 

extent  of 209-210 

Lake,  former,  in  Ralston  Desert 183 

near  Sweetwater  Range 128, 129 

Lake,  Pleistocene,  in  Gabbs  Valley 107, 108 

Grapevine  and  Funeral  ranges,  Cal..  191,194 

Ralston  Desert 183 

Little  Smoky  and  White  Pine  valleys..        79 
Lake,  Pliocene,  in  vicinity  of  Carson  . . .    124, 125 

Meadow  Valley 148 

Pancake  Range 72 

west  of  Quinn  Canyon  Range 72 

White  Mountain  Range 209, 210 

Lake,  Tertiary ,  in  Amargosa  Valley,  Cal. . .      195 

near  Grapevine  Range,  Cal 190 

Las  Vegas  Range,  geology  of 155 

Lava.    See  Igneous  rocks. 

Leach  Point  Mountains,  Cal.,  geology  of.  205-206 

Lead,  Austin  region 97 

Belmont  region 93 

Darwin  or  Argus  Range,  Cal 213 

Hamilton  district 68 

Mineral  City 54 

Spring  Mountain  Range 180 

White  Mountain  Range,  Cal 211 

Lone  Mountain,  geology  of 183-184 

Lone  Mountain  limestone,  described 20 

occurrence  of 31,  32, 37, 49 

Long  Valley  Range,  geology  of 54-67 

Manganese,  black  o.xide  of,  near  Hamilton .        68 

Mason  Butte,  geology  of 116 

Mastodon,  teeth  and  bones  of,  Las  Vegas 

Range 157 

Meadow  Valley  Canyon,  geology  of 134-136, 

139-148 

Meadow  Valley  Range,  geology  of 148 

Mesozoic  rocks,  in  E.xcelsior  Range 110-111 

Kingston  Range,  Cal 198 

Muddy  Range 137 

Pilot  Mountain  103-104 

Snake  Range 33-34 

Spring  Mountain  Range 169, 172-174 

See  afeo  Cretaceous;  Jurassic;  Trias- 
sic. 

Mesquite  Valley,  Cal.,  geology  of 202, 204 

Mineral  City,  mines  at 54 

Miocene  rocks,  in  Excelsior  Range Ill 

See  ateo  Tertiary. 
Mississippian  rocks,   in    Spring    Mountain 

Range 167 

See  also  Carboniferous. 

Mokeamoke  Ridge,  geology  of 62-68 

Monitor  Range,  geology  of 89 

Mono  Lake,  geology  of  region 218 

former  extent  of 210 

Monte  Cristo  Mountains,  geology  of 105-106 

Mormon  Canyon,  geology  of 144-145 

Mormon  Range,  geology  of 134-136 

Mountain  Spring,  geology  of  region 169, 177 

Muddy  Range,  geology  of 136-138 

Mud  Spring,  geology  of  region 160 

Mule  Spring,  geology  of  region 170, 176, 177 

Neocene  gravels,  in  Sierra  Nevada 218 

Nevada  limestone,  described 20 

occurrence  of 37,83 

Newark  Mountain,  geologic  structure  of . . .       80 


INDEX. 


227 


I'age. 

Niagara  formation,  occurrence  of 86 

Ogden  quartzite,  described 20 

Opal  Mountains,  Cal.,  geology  of 200 

Ophir  Canyon,  geologic  structure  of 90 

Ordovician  rocks,  in  Antelope  Range 37 

Desert  Range 160, 161 

Golden  Gate  Range 58 

Grant  Range 70-71 

Hot  Creek  Range 85-86 

Humboldt  Range 61 

Las  Vegas  Range 156 

Piiion  Range 88 

Quinn  Canyon  Range 70-71 

Snake  Range 33,  31 

White  Mountain  Range,  Cal 208 

See  aim  Paleozoic:  Pilurian. 

Ores,  Ellsworth  Range 103 

Eureka  district 84 

Hot  Creek  Range 87 

Reveille  region 163 

Timpahute  Range ]  50 

Toyabe  Range ' 97 

See  also  Copper,  Gold.  etc. 

Osceola,  geology  of 27-30 

gold  at 36 

Owens  Lake,  Cal.,  geology  of  region . .  210, 211, 219 

Pahranagat  Range,  geology  of 153-151 

Pahroc  Range,  geology  of 151-152 

■  Pah-L'te  Lake,  use  of  name 22 

Painted  Mesa,  geology  of 117 

Paleozoic  rocks,  in  Darwin  or  Argus  Range, 

Cal 212 

El  Paso  Range,  Cal 211 

Meadow  Valley  Canyon 110, 143, 145 

Meadow  Valley  Range 150 

Muddy  Range 137 

Panamint  Range,  Cal 201 

Reveille  Range 162 

Slate  Range,  Cal 213 

See  also  Carboniferous;   Devonian; 
Ordorician;    Permian;  Silurian. 

Panaca,  geology  of  region 143 

Panamint  Range,  Cal.,  geology  of 200-205 

Pancake  Range,  geology  of 77-81 

Patterson,  geology  of 40 

Pennsylvanian  rocks  in  Spring  Mountain 

Range 167, 172 

Permian  rocks,  in  Spring  Mountain  Range.     171, 

172,174 
See  also  Paleozoic. 

Pilot  Knob,  Cal.,  geology  of 216-218 

Pilot  Mountains,  geology  of 103-105 

Pine  Nut  Range,  geology  of 120-125 

Pinon  Range,  geology  of 88-90 

Pioche,  geology  of  region 41, 42 

geologic  structure  at 46 

Pleasant  Valley,  geology  of 29, 33-35 

Pleistocene  Lake.    See  Lake,    Pleistocene; 
Lake  Bonne^ille:  Lake  Lahon- 
tan. 
Pleistocene  rocks,  in  Funeral  Range,  Cal..      191 

Gabbs  Valley 108 

Golden  Gate  Range .57 

Grant  Range 72 

Grapevine  Range,  Cal 191 

Las  Vegas  Range 157 


Page. 
Pleistocene  rocks,  in  "Meadnw  ^■il'.■.^'y  (  an- 

yon 1 16-147 

Panamint  Range,  Cal 203 

Pancake  Range 78, 79 

Pine  Nut  Range 124 

Quinn  Canyon  Range 72 

Ralston  Desert 183 

Smith  Valley  Range 118,119 

Snake  Range 34 

Toquima  Range 91 

Walker  River  Ran^^e '..  116-117 

White  Mountain  Range,  Cal 209 

Pliocene  lake.    See  Lake,  Pliocene;    Lake 

Shoshone. 
Pliocene  rocks,  in  Can(lelaria  Mountains  . .      114 

Excelsior  Range lU 

Grant  Range 72 

Humboldt  Range 60 

Meadow  Valley  Canyon 143-146 

Meadow  Valley  Range 150 

Mormon  Range 135 

Pancake  Range  78 

Pilot  Mountains 104-105 

Pine  Nut  Range 123-125' 

Quinn  Canyon  Range 72 

Silver  Peak  Range 135 

Smith  Valley  Range 118-120 

Snake  Range 34 

Sweetwater  Range 128 

Virgin  Range 131-132 

Walker  River  Range 117 

White  Mountain  Range,  Cal 209-210 

See  also  Tertiary. 

Pogonip  Mountain,  geology  of 62-68 

geologic  section  of 63 

Pogonip  formation,  described 21 

occurrence  of..  40,42,48,49,  5.s,81,  S6,  91, 152,202 
Prospect  Mountain  limestone  and  (^-'.artzite, 

described 21 

Quartz  Peak,  geology  of 153 

Quinn  Canyon  Range,  geology  <  f 68-76 

sketch  section  of 74 

Railroad  Pass,  geologic  structure  of 83 

Railroad  Valley,  geology  of 53 

Ralston  Desert,  geology  of 181-183 

Randsburg,  Cal.,  geology  of  hills  east  (  f  . . .      210 

Ravens  Nest,  geologic  structure  at 89 

Red  Wall  limestone,  described 21 

occurrence  of 131, 133, 134, 172 

Reese  River  Range,  geology  of 98-99 

Reveille  Range,  geology  of 101-103 

Ruby  Group  of  Mountains,  use  of  name 56 

Salt,  surface  bed  of,  at  Furnace  Creek,  Cal.      101 

Saratoga  Springs,  Cal.,  geology  of 187 

Schellbourne,  geology  of 44, 45 

Schell  Creek  Range,  geology  of 38-47 

Scissors  fault,  defined 153 

Secret  Canyon  shale,  described 22 

Section,  geologic,  at  Big  Pine,  Cal 207 

Cottonwood  spring 1 6,s,  177 

Diamond  Range 83 

Good  Spring .- 171, 174 

Grand  Canyon  and  Spring  Mountain, 

correlation  of 173 

Hot  Creek 85 

near  Indian  Springs 167 

Kingston  Range,  Cal 196, 197 


228 


INDEX. 


Past. 
Section, geologic,  at  Meadow  ValleyCanyon      118 

Pogonip  Mountain G3 

Quartz  Peak 153,15-4 

Saratoga  Springs,  Cal 187 

near  Sehellbourne 39 

near  Stampede  Gap 41 

Timpahute  Range 159 

Virginia  Range 130 

Shoshone,  Lake  ( Pliocene) 104, 186, 209-210 

Sierra  Nevada,  geology  of 218 

Silurian  rocks,  in  Antelope  Range 37 

Desert  Range 160-161 

Diamond  Range 83 

Egan  Range 48-49 

Golden  Gate  Range 57-58 

Grant  Range 69-71 

Grapevine  Range 188 

Hike  Range 152 

Hot  Greek  Range 85-86 

Las  Vegas  Range 155, 156 

Lone  Mountain 1S4 

Pahranagat  Range 153 

Pahroc  Range 152 

Panamint  Range,  Cal 231 ,  202 

Pinon  Range 88 

Quinn  Canyon  Range C9-71 

Schell  Creek  Range 40-43 

Sierra  Nevada 218 

Silver  Peak  Range 185 

Snake  Range 30-32 

Timpahute  Range 159 

Toquima  Range 91 

Toyabe  Range 94, 95 

White  Mountain  Range,  Cal 208 

White  Pine  Range C3 

Worthington  Mountains 76 

Sec  also  Ordovician;  Paleozoic. 

:Silver,  in  Austin  region 97 

Belmont  region 93 

Cherry  Creek 54 

Darwin  or  Angus  Range,  Cal 213 

Mineral  City 54 

Opal  or  Clarks  Peak  Mountains,  Cal 200 

Panamint  Range,  Cal 205 

Silver  Peak  Range 186 

Spring  Mountain  Range 180 

Toyabe  Range 97 

Treasure  Hill 68 

White  Mountain  Range,  Cal 211 

Silver  Peak  Range,  geology  of 184-186 

;Slate  Range,  Cal.,  geology  of 204, 213 

Smith  Valley  Range,  geology  of 117-120 

Snake  Range,  geology  of 25-36 

Sodaville,  geology  of  region 103, 104 

Spring  Mountain  Range,  geology  of 164-180 

.  sketch  sections  of 176-179 

Springs,  on  Snake  Range 25, 26 

hot,  on  Golden  Gate  Range 58, 59 

hot,  on  Hot  Creek  Range 87 

"warm,  on  Spring  Mountain  Range 165 

Stampede  Gap,  geology  of 41,43,46 

Stanton,  T.  W.,  cited 109,110,123 

Star  Peak  formation,  described 22 

occurrence  of 101, 123 

Stonewall  Mountain,  geology  of 182 


Page. 
Structure,   geologic,   in  Amargosa  Valley, 

Cal 195 

Antelope  Range 38 

Burnt  Rock  Mountains,  Cal 206 

Desert  Range '. 161 

Egan  Range 53-54 

Ellsworth  Range 102-103 

El  Paso  Range,  Cal 216 

Excelsior  Range 112 

Funeral  Range,  Cal 192-194 

Golden  Gate  Range 59 

Grant  Range 74-76 

Grapevine  Range,  Cal 192-194 

Highland  Range 45-47 

Hiko  Range 153 

Hot  Creek  Range 87 

Humboldt  Range CI 

Kingston  Range 199 

Las  Vegas  Range 157-159 

Leach  Point  Mountains,  Cal 206 

Long  Valley  Range 53-57 

Meadow  Valley  Range 150-151 

Mormon  Range 135-136 

Muddy  Range 138 

Pahroc  Range 152 

Panamint  Range,  Cal 204 

Pancake  Range 80 

Piiion  Range 89 

Quinn  Can  yon  Range 73-76   - 

Schell  Creek  Range :  44-47 

Sierra  Nevada 220 

Snake  Range 35-36 

Spring  Mountain  Range 175-180 

Timpahute  Range 160 

Toquima  Range 92-93 

Toyabe  Range 96 

Virgin  Range 132-133 

-  White  Mountain  Range,  Cal 212 

White  Pine  Range G5-68 

Worthington  Mountains 77 

Subaerial  accumulations,  disadvantages  for 

study 139-140 

in  Gabbs  Valley 108 

in  Long  Valley  Range 55 

in  Nevada  valleys,  generally 139 

in    Quinn  Canyon   Range   and    Grant 

Range 72 

Sweetwater,  geology  of  region 119, 127  - 

Sweetwater  Range,  geology  of 125-129 

Tertiary  rocks  in  Amargosa  Valley,  Cal  ...      195 

Candelaria  Mountains 114 

El  Paso  Range 215 

Excelsior  Range 109-111 

Funeral  Range,  Cal 189-191, 193 

Gabbs  Valley 107 

Grapevine  Range,  Cal 189-191 

Hot  Creek  Range 86 

Kawich  Range 181 

Kingston  Range,  Cal 198 

Las  Vegas  Range 157 

Monte  Cristo  Mountains IOj 

Muddy  Range 137 

Panamint  Range 201, 202 

Pancake  Range 7S-79 

Pilot  Mountains 103-104 

Ralston  Desert 183 


INPEX. 


229 


Page. 

Tertiary  rocks  in  Reveille  Range 1G3 

Silver  Peak  Range 1S5 

Slate  Ra'nge 213 

Snake  Range 38-34 

Toyabe  Range 95 

Virgin  River  Valley 132 

Sec  also  Eocene;  Miocene;  Neocene; 
Pliocene. 

Timpahute  Range,  geology  of 159-lGO 

Tonto  formation,  described 18, 22 

occurrence  of 133 

Toqiiima  Range,  geology  of 89-93 

Toyabe  Range,  geology  of 93-97 

Treasure  Hill,  geologic  structure  of 66-58 

Triassic  rocks.    .Sec  also  Mesozoic. 

Triassic  rocks  in  Ells^vorth  Range 101,102 

Muddy  Range 137 

Pine  Nut  Range 122-123 

Sierra  Nevada 218,  219 

Spring  Mountain  Range 172, 174 

Virginia  Range 130 

White  Mountain  Range,  Cal 208-209 

Truckee  formation,  de.scribed 22 

Tvbo,  gcologv  of 86 


Page. 
Uiyabi  Pass,  geology  of 33 

structure  of 35 

Unkar  formation,  described IS,  19, 23 

occurrence  of 133 

Virginia  Range,  geology  of 129-130 

Virgin  Range,  geology  of 131-133 

Wahweah  Range,  geology  of 89-90 

Walker  River  Range,  geology  of 115-117, 118 

Wasatch  limestone,  described 23 

Wassuck  Range.    Sec  Walker  River  Range. 

Water  supply,  springs  on  Snake  Range 25, 26 

Weber  conglomerate,  described 23 

Wheeler  Peak,  geology  of 25, 27, 31 ,  32, 35 

White  Bluff  Spring,  geology  of  region 164 

White  Mountain  Range,  Cal.,  geology  of.  206-212 
White  Pine  formation,  described 23-24 

occurrence  of 78, 80,  £3 

White  Pine  Range,  geology  of G1-6S 

White  Pine  Valley,  situation  of 77 

Whites  Peak,  geologic  structure  of 45 

Wileys,  geology  of  region 127 

Wind,  effects  of.    See  Subaerial  accumula- 
tions. 
Worthington  Mountains,  geology  of 76-77 


o 


PUBLICATIONS  OF  UNITED  STATES  GEOLOGICAL  SURVEY. 

[Bulletin  No.  208.1 

The  serial  publications  of  tlie  United  States  (xeological  Survey  consist  of  (1)  Annual 
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tions; X,  Water  power;  0,  Underground  waters;  P,  Hydrographic  progress  reports. 
This  bulletin  is  the  twenty-seventh  number  in  Series  B,  the  complete  list  of  which. 
follows.      (PP  —  Professional  Paper;  B  =  Bulletin;  AVS  =  Water-Sujaply  Paper.) 

SERIES    B,   IJESCRIPTIVE    (lEOLOCiV. 

B  23.  Observations  on  the  junction  between  the  Eastern  sandstone  and  the  Keweenaw  series  on 

Keweenaw  Point,  Lake  Superior,  by  R.  D.  Irving  and  T.  C.  Chamberlin.    1885.    124  pp.,  17  pis. 
B  33.  Notes  on  geology  of  northern  California,  by  .J.  S.  Diller.    1886.    23  pp.     (Out  of  stock.) 
B  39.  The  upper  beaches  and  deltas  of  Glacial  Lake  Agassiz,  by  Warren  Upham.    1887.    84  pp.,  1  pi. 

(Out  of  stock.) 
B  40.  Changes  in  river  courses  in  Washington  Territory  due  to  glaciation,  by  Bailey  Willis.    1887. 

10  pp.,  4  pis.     (Out  of  stock.) 
B  4').  The  present  condition  of  knowledge  of  the  geology  of  Texas,  by  R.  T.  Hill.    1887.    94  pp.     (Out 

of  stock.) 
B  .53.  The  geology  of  Nantucket,  by  N.  S.  Shaler.    1889.    55  pp.,  10  pis.     (Out  of  .stock.) 
B  57.  A  geological  reconnaissance  in  southwe.stern  Kansas,  by  Robert  Hay.    1890.     '19  pp.,  2  pis. 
B  58.  The  glacial  boundary  in  western  Pennsylvania,  Ohio,  Kentucky,  Indiana,  and  Illinois,  by  G.  F. 

Wright,  with  introduction  by  T.  C.  Chamberlin.    1890.    112  pp.,  8  pis.     (Out  of  stock.) 
B  67.  The  relations  of  the  traps  of  the  Newark  system  in  the  New  Jersey  region,  by  N.  H.  Darton. 

1890.    82  pp. 
B  104.  Glaciation  of  the  Yellowstone  Valley  north  of  the  Park,  by  W.  H.  Weed.    1893.    41  pp.,  4  pis. 
B  108.  A  geological  reconnaissance  in  central  Washington,  by  I.  C.  Russell.    1893.    108  pp.,  12  pis. 

(Out  of  stock.) 
B  119.  A  geological  reconnaissance  in  northwest  Wyom.ing,  by  G.  H.  Eldridge.    1894.    72  pp.,  4  pis. 
B  137.  The  geology  of  the  Fort  Riley  Military  Reservation  and  vicinity,  Kansas,  by  Robert  Hay. 

1896.     35  pp.,  8  pis. 
B  144.  The  moraines  of  the  Missouri  Coteau  and  their  attendant  depo.'-its  by  J.  E.  Todd.    1896.    71 

pp.,  21  pis. 
B  158.  The  moraines  of  southeastern  South  Dakota  and  their  attendant  deposits,  by  J.  E.  Todd. 

1899.     171pp.,  27  pis. 
B  159.  The  geology  of  eastern  Berkshire  County,  Massachusetts,  by  B.  K.  Emerson.     1899.     139  pp., 

9  pis. 
B  165.  Contributions  to  the  geology  of  Maine,  by  H.  S.  Williams  and  H.  E.  Gregory.     1900.     212  pp., 

14  pis. 
WS  70.  Geology  and  water  resources  of  the  Patrick  and  Goshen  Hole  quadrangles  in  eastern  Wyom- 
ing and  western  Nebraska,  by  G.  I.  Adams.    1902.    50  pp.,  11  pis. 
B  199.  Geology  and  water  resources  of  the  Snake  River  Plains  of  Idaho,  by  I.  C  Ktissell.    1902.    192 

pp.,  25  pis. 

I 


II  ADVERTISEMENT. 

PP  1.  Preliminary  report  on  the  Ketchikan  mining  district,  Alaska,  with  an  introductory  sketch  of 
the  geology  of  southeastern  Alaska,  by  A.  H.  Brooks.    1902.    120  pp.,  2  pis. 

PP  2.  Reconnaissance  of  the  northwestern  portion  of  Seward  Peninsula,  Alaska,  by  A.  J.  Collier. 
1902.    70  pp.,  11  pis. 

PP  3.  Geology  and  petrography  of  Crater  Lake  National  Park,  by  J.  S.  Diller  and  H.  B.  Patton. 
1902.    167  pp.,  19  pis. 

PP  10.  Reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska,  by  way  of  Ball,  Kanuti, 
Allen,  and  Kowak  rivers,  by  VV.  C.  Mendenhall.    1902.    68  pp.,  10  pis. 

PP  11.  Clays  of  the  United  States  east  of  the  Mississippi  River,  by  Heinrich  Ries.    1903.    298  pp.,  9  pis. 

PP  12.  Geology  of  the  Globe  copper  district,  Arizona,  by  F.  L.  Ransome.    1903.    168  pp.,  27  pis. 

PP  13.  Drainage  modifications  in  southeastern  Ohio  and  adjacent  parts  of  West  Virginia  and  Ken- 
tucky, by  W.  G.  Tight.    1903.    Ill  pp.,  17  pis. 

B  208.  Descriptive  geology  of  Nevada  south  of  the  fortieth  parallel  and  adjacent  portions  of  Cali- 
fornia, by  J.  E.  Spurr.    1903.    229  pp.,  8  pis. 

Correspondence  should  be  addressed  to 

The  Director, 

United  States  Geological  Survey, 

Washington,  D.  C. 
Hay,  1903. 


LIBRARY  CATALOGUE  SLIPS. 

[Mount  each  slip  upon  a  separate  card,  placing  the  subject  at  the  top  of  the 
second  slip.  The  name  of  the  series  should  not  be  repeated  on  the  series 
card,  but  add  the  additional  numbers,  as  received,  to  the  first  entry.] 


Spurr,  Josiah  Edward. 

-.  .  .  Descriptive  geolog\^  of  Nevada  south  of  the  for- 
tieth parallel  and  adjacent  portions  of  California,  by 
Josiah  Edward  Spurr.  Washington,  Gov't  print,  off., 
1903. 

229,  III  p.     8  pi.  incl.  maps,  25  fig.     23*'^'".     (U.  S.  Geological  survey. 
Bulletin  no.  208. ) 
IMap  in  pocket. 
Subject  series  B,  Descriptive  geology,  27. 


Spurr,  Josiah  Edward. 

.  .  .  Descriptive  geolog}^  of  Nevada  south  of  the  for- 
tieth parallel  and  adjacent  portions  of  California,  by 
Josiah  Edward  Spurr.  Washington,  Gov't  print,  off., 
1903. 

229,  III  p.     8  pi.  incl.  maps,  25  fig.     23*'^".     (U.  S.  Geological  survey. 
Bulletin  no.  208. ) 
Map  in  pocket. 
>Subject  series  B,  Descriptive  geology,  27. 


U.  S.  Geological  survey. 

Bulletins. 
I    no.  208.  Spurr,  J,  E.     Descriptive  geology  of  Nevada 
°^  south  of  the  fortieth  parallel  and  adjacent  por- 

tions of  California.     1903. 


^        U.  S.  Dept.  of  the  Interior. 

£  see  also 

I    U.  S.  Geological  survey. 

Bull.  208—03 16 


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